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H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> abiotic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Non-living; describes a property of an environment that is purely physical or chemical, such as light, air, water, or nutrients. <div class="px10">© 2009 Nature Education </div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/absolute-risk-63">absolute risk</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In epidemiological studies, the probability that an individual will develop a particular condition, such as a disease or some other outcome, based on genetic profile, behavioral patterns, and/or test results. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> abundant center distribution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The highest population densities are observed in the range core, but the species becomes increasingly rare towards its range margin. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> acceptor arm </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The arm in tRNA to which an amino acid attaches. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> accessory chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any extra chromosome in the karyotype of an organism. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> accumulators </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Plants containing intermediate concentrations of certain chemical elements (frequently metals or metallic compounds). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> acentric chromatid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Lacks a centromere; produced when crossing over takes place within a paracentric inversion. The acentric chromatid does not attach to a spindle fiber and does not segregate in meiosis or mitosis, so it is usually lost after one or more rounds of cell division. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> acetylation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzymatic reaction that results in the addition of an acetyl group to a biochemical. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> acidic activation domain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Commonly found in some transcriptional activator proteins, a domain that contains multiple amino acids with negative charges and stimulates the transcription of certain genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> acrocentric chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromosome with a centromere located off-center, resulting in longer arms on one side than another. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> action potential </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An electric signal that travels along neurons; a continuously regenerated impulse that transfers information throughout the nervous system of organisms. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> activation domain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Part of a transcription factor that is modular and independent from the DNA-binding activity. An activation domain stimulates PolII activity at the locus. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> activator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein in eukaryotic cells that binds to consensus sequences in regulatory promoters or enhancers and affects transcription initiation by stimulating or inhibiting the assembly of the basal transcription apparatus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> active restoration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Accelerating the process or attempting to change the trajectory of succession. For example, mine tailings would take so long to recover passively that active restoration is usually appropriate. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/adaptation-229">adaptation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process of change in a population that occurs under selective forces over time and through multiple generations, to produce genetic differences in future generations; the change in a population that increases fitness. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> adaptive evolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The adjustment of an organism to its environment, or the process by which it enhances such fitness. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> adaptive immunity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Immunity acquired after exposure to a pathogen, or some foreign antigen. Distinct from native immunity. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> adaptive landscape </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A three-dimensional depiction of population mean fitness as a function of genotype or phenotype, in which the horizontal axes are allele frequencies at two loci or two phenotypic traits, and the vertical axis is population mean fitness. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> adaptive mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process by which a specific environment induces mutations that enable organisms to adapt to the environment. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> adaptive peak </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The maxiumum mean fitness of a population, calculated with allele frequencies or traits. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> adaptive radiation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Evolutionary divergence of members of a single phylogenetic lineage into a variety of different adaptive forms; usually the taxa differ in the use of resources or habitats, and have diverged over a relatively short interval of geological time. The term "evolutionary radiation" describes a pattern of rapid diversification without assuming that the differences are adaptive. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> adaptive topography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A three-dimensional depiction of population mean fitness as a function of genotype or phenotype, in which the horizontal axes are allele frequencies at two loci or two phenotypic traits, and the vertical axis is population mean fitness (synonym: adaptive topography). <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> adaptive trait </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait that contributes either directly or indirectly to an individual's fitness. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> adaptive valley </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A set of allele frequencies at which mean fitness has a minimum. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> adaptive zone </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A set of similar ecological niches occupied by a group of (usually) related species, often constituting a higher taxon. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> addition rule </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> States that the probability of any of two or more mutually exclusive events occurring is calculated by adding the probabilities of the individual events. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> additive effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The magnitude of the effect of an allele on a character, measured as half the phenotypic difference between homozygotes for that allele compared with homozygotes for a different allele. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> additive genetic correlation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of the degree to which two traits are affected by the same genes (pleiotropy) or pairs of genes (linkage disequilibrium). Selection on one trait produces an evolutionary change in all traits that have an additive genetic correlation with the selected trait. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> additive genetic variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The genetic variance in a character that is attributable to additive effects of alleles, and that determines how different progeny are from their parents. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> additive genetic variance-covariance matrix </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A square matrix with additive genetic variances for the traits on the diagonal and additive genetic covariances on the off-diagonal. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> additivity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The type of gene action in which the alleles at a locus do not affect each other's expression or the expression of alleles at other loci; in other words, gene action with no dominance or epistasis. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> adenine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A purine base in DNA and RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> adenosine-3',5'-cyclic monophosphate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Modified nucleotide that functions in catabolite repression. Low levels of glucose stimulate high levels of cAMP; cAMP then attaches to CAP, which binds to the promoter of certain operons and stimulates transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> adjacent-1 segregation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N1 and N2 and the chromosomes containing the translocated segments are T1 and T2, then adjacent-1 segregation takes place when N1 and T2 move toward one pole and T1 and N2 move toward the opposite pole. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> adjacent-2 segregation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N1 and N2 and the chromosomes containing the translocated segments are T1 and T2, then adjacent-2 segregation takes place when N1 and T1 move toward one pole and T2 and N2 move toward the opposite pole. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/adult-onset-76">adult-onset</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a condition in which the phenotype does not manifest itself until later in life. The physical manifestation of such a condition is not present until after puberty. </div> </div> </div> <div class="wrap"> <strong> affinity chromatography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method of separating biochemical components based on specific interactions between the components of the biochemical mixture and other molecules (e.g., antigen-antibody or receptor-ligand). <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> AFLP </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic markers detected by cleaving DNA with one or more restriction enzymes and then amplifying some of these fragments by PCR using primers with random nucleotide sequences. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> African sleeping sickness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A vector-borne disease caused by parasites from the genus Trypanosoma. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/aging-aging-171">aging</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The decline in population or organismal fitness or tissue/cell health over time. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> alder </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A common flowering plant along the successional chain of species for a forest. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/alkaptonuria-black-urine-disease-195">alkaptonuria</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A single-gene disorder identified by Archibald Garrod that is characterized by dark urine. Garrod first coined the term "inborn error in metabolism" to describe this and other congenital, inherited disorders that affect metabolic pathways. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/allele-48">allele</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An alternate form of a gene; a single gene can have multiple alleles, or versions. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/allele-frequency-298">allele frequency</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A number that represents the incidence of a gene variant in a population. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> alleles </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Alternative versions of genes; located at specific positions on a specific chromosome; interactions between allelic expression lead to trait phenotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> allelopathy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Biochemical production by a plant which alters growth and survival of other plants or itself. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> allometric coeffient </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> (a) in the linear equation, log y = a log x + log b, the slope of the line. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> allometric equations </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An equation to aid in the calculation of the change in proportion of various parts of an organism as a consequence of growth. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> allometric growth </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The growth of some feature or body part during development at a rate different from that of another feature. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> allometry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Biological scaling relationships, be it for morphological traits, physiological traits or ecological traits; the study of the relationship between size and shape. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> allopatric </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Of a population or species, occupying a geographic region different from that of another population or species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> allopatric speciation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A differentation process whereby one species becomes two usually due physical isolation of the populations involved. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> allopolyploid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A polyploid in which the several chromosome sets are derived from more than one species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> allosteric protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that changes its conformation on binding with another molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> alpha diversity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Within-habitat diversity. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> alternate segregation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N1 and N2 and the chromosomes containing the translocated segments are T1 and T2, then alternate segregation takes place when N1 and N2 move toward one pole and T1 and T2 move toward the opposite pole. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> alternation of generations </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Complex life cycle in plants that alternates between the diploid sporophyte stage and the haploid gametophyte stage. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> alternative processing pathway </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of several pathways by which a single pre-mRNA can be processed in different ways to produce alternative types of mRNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> alternative splicing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The varieties of ways that pre-mRNA is cut and reassembled to make different mRNA sequences, and therefore alternate expressions of a gene. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> altruism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Conferral of a benefit on other individuals at an apparent cost to the donor. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> altruistic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Behavior by an individual that may reduce it.s immediate direct fitness but increases the fitness of another. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/alu-alu-element-236">Alu</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Part of a family of short, interspersed repeats, these are the most abundant sequence repeats in the human genome (making up 5%.10% of the total). Alu sequences can be propagated by retrotransposition, although most are sterile, or DNA "fossils." <div class="px10">Mel F. Greaves & Joe Wiemels</div> </div> </div> </div> <div class="wrap"> <strong> amanitin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A highly poisonous polypeptide that selectively inhibits the activity of mammalian RNA polymerase. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> Ames test </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Test in which special strains of bacteria are used to evaluate the potential of chemicals to cause cancer. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/amino-acid-115">amino acid</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Amino acids are small molecules that serve as building blocks of proteins </div> </div> </div> <div class="wrap"> <strong> aminoacyl (A) site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of three sites in a ribosome occupied by a tRNA in translation. All charged tRNAs (with the exception of the initiator tRNA) first enter the A site in translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> aminoacyl-tRNA synthetase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme that attaches an amino acid to a tRNA. Each aminoacyl-tRNA synthetase is specific for a particular amino acid. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> amniocentesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Procedure used for prenatal genetic testing to obtain a sample of amniotic fluid from a pregnant woman. A long sterile needle is inserted through the abdominal wall into the amniotic sac to obtain the fluid. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> anagenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Evolution of a feature within a lineage over an arbitrary period of time. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> analysis of variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Statistical technique for testing for differences among the means of several groups with respect to a continuous variable. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> analytical model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A model in which the relationships among variables are defined using equations. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/anaphase-179">anaphase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Anaphase is the fourth phase of mitosis, which is a process that separates the duplicated genetic material carried in the nucleus of a parent cell into two, identical daughter cells </div> </div> </div> <div class="wrap"> <strong> anaphase I </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of meiosis I. In anaphase I, homologous chromosomes separate and move toward the spindle poles. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> anaphase II </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of meiosis II. In anaphase II, chromatids separate and move toward the spindle poles. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> ancestral species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A species at the root of a clade of related organisms. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/aneuploidy-aneuploid-162">aneuploidy</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Change from the wild type in the number of chromosomes; most often an increase or decrease of one or two chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> angiosperms </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of seed plants that produce flowers and fruits for reproduction; the fruit encloses the seed and typically increases chances of seed distribution. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/animal-development-development-91">animal development</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process whereby a fertilized egg undergoes cell division and cellular differentiation to generate the different tissue types of a fully functional complex organism. </div> </div> </div> <div class="wrap"> <strong> animal production </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A subcategory of secondary production, the production of an animal population. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> antagonistic interaction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An interaction between two organisms that benefits one to the detriment of the other. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> antagonistic relationships </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Relationships in which organisms compete for resources, spread disease to their neighbors, or consume each other. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> antagonistic selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A source of natural selection that opposes another source of selection on a trait. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> Antennapedia complex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cluster of five homeotic genes in fruit flies that affects development of the adult fly's head and anterior thoracic segments. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Antennapedia homeodomain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A sequence-specific transcription factor from Drosophila melanogaster. The wild-type Antennapedia homeodomain complex works to initiate a series of transcription events that results in anterior-posterior polarity in the organism. </div> </div> </div> <div class="wrap"> <strong> anthropogenic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A condition, process, or result stemming from human activity, such as air pollution or agriculture. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/antibiotic-resistance-237">antibiotic resistance</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Heritable changes in bacteria that allow them to withstand antibiotic treatments that would normally kill them. </div> </div> </div> <div class="wrap"> <strong> antibody </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Produced by a B cell, a protein that circulates in the blood and other body fluids. An antibody binds to a specific antigen and marks it for destruction by making it easier for a phagocytic cell to ingest the antigen. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> anticipation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Increasing severity or earlier age of onset of a genetic trait in succeeding generations. For example, symptoms of a genetic disease may become more severe as the trait is passed from generation to generation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> anticodon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence of three nucleotides in tRNA that pairs with the corresponding codon in mRNA in translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> antifeedants </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A substance that inhibits normal feeding behavior. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> antigen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Substance that is recognized by the immune system and elicits an immune response. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> antigenic drift </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process by which circulating influenza viruses are constantly changing, which allows the viruses to cause annual epidemics of illness. Antigenic drift occurs when mutations accumulate in the hemagglutinin and neuraminidase genes that alter the antigenicity of these proteins such that the "drifted" strains are no longer neutralized by antibodies that were specific for previously circulating strains. <div class="px10">Kanta Subbarao & Tomy Joseph</div> </div> </div> </div> <div class="wrap"> <strong> antigenic shift </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process by which a new influenza A virus hemagglutinin subtype (with or without an accompanying new neuraminidase subtype) is introduced into the human population, which lacks prior experience of and immunity to the subtype. Antigenic shift can occur as a result of the direct introduction of an influenza virus from an animal or avian host into humans, or by the exchange or reassortment of gene segments between human and non-human influenza viruses when they co-infect animals or humans. <div class="px10">Kanta Subbarao & Tomy Joseph</div> </div> </div> </div> <div class="wrap"> <strong> antiparallel </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a characteristic of the DNA double helix in which the two polynucleotide strands run in opposite directions. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> antisense RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small RNA molecule that base pairs with a complementary DNA or RNA sequence and affects its functioning. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> antiterminator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein or DNA sequence that inhibits the termination of transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> apomixis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Parthenogenetic reproduction in which an individual develops from one or more mitotically produced cells that have not experienced recombination or syngamy. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> apomorphic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Having a derived character or state, with reference to another character or state. See also synapomorphy. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> apoptosis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Programmed cell death, in which a cell degrades its own DNA, the nucleus and cytoplasm shrink, and the cell undergoes phagocytosis by other cells without leakage of its contents. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> aposematic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Coloration or other features that advertise noxious properties; warning coloration. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> aposematic coloration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Antipredator adaptation in which conspicuous markings on an animal that is poisonous or unpalatable serve to discourage potential predators. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> applied restoration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A multi-step process, which may include some or all of these stages: assessing the site, formulating project goals, removing sources of disturbance, restoring processes/disturbance cycles, rehabilitating substrates, restoring vegetation, and monitoring and maintenance. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> aptamer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Nucleic acid that binds to a specific target molecule. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/archaea-242">Archaea</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the three primary divisions of life. Archaea consist of unicellular organisms with prokaryotic cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> area effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The larger a place is, the more species it can support. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> array comparative genomic hybridization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Similar to conventional comparative genomic hybridization (CGH), but during hybridization, cloned chromosomal DNA fragments (about 200 kb in size) replace the metaphase chromosomes. This method offers greater sensitivity and resolution than conventional CGH in detecting copy number changes. <div class="px10">Nature Reviews Cancer</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/artificial-selection-230">artificial selection</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Selective breeding of organisms to produce domesticated animals with more desirable traits; selective breeding to test for genetic variation and covariation in a population. Compare to natural selection. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/asexual-221">asexual</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A term describing reproduction that does not involve gene transfer between parent cells. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> aspect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A characteristic among many that characterize a person or object; more specifically, the angle of view on and object or face. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> assemblages </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species that share an attribute of habitat or taxonomic similarity. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> assisted reproductive technologies </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Procedures or methods that promote succesful fertilization and pregnancy in humans. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> association study </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In genetics, a case-control study in genotype frequencies are compared between healthy and diseased individuals; SNPs that form haplotypes are a typical focus for comparison. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> assortative mating </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Nonrandom mating on the basis of phenotype; usually refers to positive assortative mating, the propensity to mate with others of like phenotype. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> asymmetrical response </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A common result in artificial selection experiments in which there is a greater response to selection in one direction than there is in the opposite direction for the same trait. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> atavism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The reappearance in an organism of characteristics that are present in the organism's remote ancestors. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/atp-318">ATP</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Adenosine 5-triphosphate, or ATP, is the principal molecule for storing and transferring energy in cells. </div> </div> </div> <div class="wrap"> <strong> attached-X </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A pair of X chromosomes in Drosophila melanogaster that are connected together at one end and inherited jointly. </div> </div> </div> <div class="wrap"> <strong> attachment site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Special site on a bacterial chromosome where a prophage may insert itself. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> attenuation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of gene regulation in some bacterial operons, in which transcription is initiated but terminates prematurely before transcription of the structural genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> attenuator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Secondary structure that forms in the 5' untranslated region of some operons and causes the premature termination of transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> autoantibodies </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Antibodies that form in response to antigens in one's own tissue; antibodies that attack cells native to the organism. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> autoimmune disease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Characterized by an abnormal immune response to a person's own (self) antigen. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> autonomous element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transposable element that is fully functional and able to transpose on its own. DNA sequence that confers the ability to replicate; contains an origin of replication. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> autopolyploidy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Condition in which all the sets of chromosomes of a polyploid individual possessing more than two haploid sets are derived from a single species. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> autoradiography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method for visualizing DNA or RNA molecules labeled with radioactive substances. A piece of X-ray film is placed on top of a slide, gel, or other substance that contains DNA labeled with radioactive chemicals. Radiation from the labeled DNA exposes the film, providing a picture of the labeled molecules. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> autosomal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait resulting from a chromosome that is not a sex chromosome. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> autosomal dominant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An inheritance pattern through generations of a family that indicates a trait is passed via an autosome, and is dominant to other traits. The inherited trait can affect males and females equally. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> autosomal inheritance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic transmission of genes on autosomes (nonsex chromosomes). <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> autosomal recessive </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An inheritance pattern through generations of a family that indicates a trait is passed via an autosome, and is recessive to other traits. The inherited trait can affect males and females equally. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> autosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any chromosome in the set of chromosomes that is not a sex chromosome. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> autotrophs </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that obtain energy from the sun or from the oxidation of inorganic substances; organisms that convert energy into nutrients through a series of chemical reactions. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> auxillary chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Former name for an unpaired sex chromosome. Used today to indicate an artificial "extra" (i.e., engineered) chromosome. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> auxotroph </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterium or fungus that possesses a nutritional mutation that disrupts its ability to synthesize an essential biological molecule; cannot grow on minimal medium but can grow on minimal medium to which has been added the biological molecule that it cannot synthesize. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="B"><div class="padleft10px fleft bold px15">B</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> B-cell </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Particular type of lymphocyte that produces humoral immunity; matures in the bone marrow and produces antibodies. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> B-DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Right-handed helical structure of DNA that exists when water is abundant; the secondary structure described by Watson and Crick and probably the most common DNA structure in cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> B1 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cross in which an F1 or F1' individual is mated to one of its parents (P1) or to another individual that is genetically identical to one of its parents. <div class="px10">Terry McGuire</div> </div> </div> </div> <div class="wrap"> <strong> B2 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cross in which an F1 or F1' individual is mated to one of its parents (P2) or to another individual that is genetically identical to one of its parents. <div class="px10">Terry McGuire</div> </div> </div> </div> <div class="wrap"> <strong> backcross </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mating between an F1 or F1' individual to one of its parents (P1 or P2) or to another individual that is genetically identical to one of its parents. The term "backcross" may be used as a verb (describing the process of setting up the required mating) or as a noun to describe the mating or to describe the progeny that result from such a hybrid cross. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> backcross 1 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cross of an F1 or F1' individual to a P1 individual. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> backcross 2 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cross of an F1 or F1' individual to a P2 individual. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> background extinction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A long-prevailing rate at which taxa become extinct, in contrast to the highly elevated rates that characterize mass extinction. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> background selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Elimination of deleterious mutations in a region of the genome; may explain low levels of neutral sequence variation. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/bacteria-5">bacteria</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Single-celled prokaryotes that can be free-living or live as parasites. </div> </div> </div> <div class="wrap"> <strong> bacterial artificial chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cloning vector used in bacteria that is capable of carrying DNA fragments as large as 500 kb. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> bacterial colony </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Clump of genetically identical bacteria derived from a single bacterial cell that undergoes repeated rounds of division. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/bacteriophage-phage-293">bacteriophage</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacteriophage; a type of virus that infects bacteria. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> bag cell hormones </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Hormones that control the onset of egg-laying behavior. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> balance hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proposes that much of the molecular variation seen in natural populations is maintained by balancing selection that favors genetic variation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> balanced lethals </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The arrangement of two recessive lethal alleles such that the alleles lie in repulsion; here, it is essentially as if the organism was a heterozygote for the lethal allele. Homozygosity would result in death of the organism. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> balanced polymorphism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The persistence of an multiple alleles in a population due to reproductive advantage of the heterozygote over any homozygote. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> balanced translocation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When pieces of chromosomes are rearranged but no genetic material is gained or lost in the cell. <div class="px10">Genetics Home Reference</div> </div> </div> </div> <div class="wrap"> <strong> balancing selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of natural selection that maintains polymorphism at a locus within a population. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> Barr body </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Condensed, darkly staining structure that is found in most cells of female placental mammals and is an inactivated X chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> basal transcription apparatus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Complex of transcription factors, RNA polymerase, and other proteins that assemble on the promoter and are capable of initiating minimal levels of transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> base analog </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chemical substance that has a structure similar to that of one of the four standard bases of DNA and may be incorporated into newly synthesized DNA molecules in replication. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> base substitution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of mutation that changes the identity of a single base in a DNA sequence, so that the number of bases remains the same but the codon and downstream amino acid are altered. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> base-excision repair </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA repair that first excises modified bases and then replaces the entire nucleotide. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> base-pairing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The interaction of complementary nitrogen-containing bases, such as cytosine and guanine, in the formation of double stranded nucleic acids; occurs in DNA replication. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Bateman's PRINCIPLE </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Female reproduction is primarily limited by their access to resources to nourish and produce large gametes, whereas male reproduction is mainly limited by access to females. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> batesian mimicry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A situation in which a harmless species has evolved to imitate the warning signals of a harmful or distasteful species directed at a common predator. It is named after the English naturalist Henry Walter Bates, after his work in the rainforests of Brazil. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Beckwith-Wiedemann Syndrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Syndrome of unknown etiology characterized by the presence of macroglossia (large tongue), visceromegaly (large organs), macrosomia (large body size), and hypoglycemia. Patients show an increased susceptibility to tumor development. </div> </div> </div> <div class="wrap"> <strong> behavioral homeostasis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Perceptions of need that usually link directly to physiological control systems. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> benthic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Inhabiting the bottom, or substrate, of a body of water. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> beta diversity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Between-habitat diversity. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Bicoid homeodomain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The maternally transcribed gene bicoid organizes anterior development in Drosophila. Bicoid encodes a homeodomain-containing transcriptional factor, its gradient acting to position the transcription of gap and pair rule genes along the anterior-posterior axis. <div class="px10"> Alex Spirov</div> </div> </div> </div> <div class="wrap"> <strong> bidirectional replication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Replication at both ends of a replication bubble. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> binomial expansion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a statistical method of examining characteristics in a population. Hardy-Weinberg used this technique to provide a mathematical model of population genetics. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/biodiversity-32">biodiversity</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic and phenotypic variation both within and among species, plus the variety of ecosystems created by these species. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/bioethics-79">bioethics</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of the ethical, moral, and societal implications of biological research and discovery. </div> </div> </div> <div class="wrap"> <strong> biogeography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of the geographic distribution of organisms. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/bioinformatics-192">bioinformatics</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Synthesis of molecular biology and computer science that develops databases and computational tools to store, retrieve, and analyze nucleic acid and protein sequence data. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> biological observations </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Data collected during the course of a biological experiment or survey; can be quantitative or qualitative. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> biological species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A population or group of populations within which genes are actually or potentially exchanged by interbreeding, and which are reproductively isolated from other such groups. See also species, phylogenetic species concept. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> biomass </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The total mass of all organisms, plant, animal or otherwise, in a given area. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> biomes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Regions of similar climate and dominant plant types. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> biomimicry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of natural products that provide solutions to human needs. For example, shark skin provided the model for hydrodynamic swimming suits. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/biotechnology-151">biotechnology</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Use of biological processes, particularly molecular genetics and recombinant DNA technology, to produce products of commercial value. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> biotic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pertaining to living organisms in an environment. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> birth defects </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any malformations or defects of development found at birth. </div> </div> </div> <div class="wrap"> <strong> bithorax complex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cluster of three homeotic genes in fruit flies that influences the adult fly's posterior thoracic and abdominal segments. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> bivalent </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a synapsed pair of homologous chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> BLAST </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Basic Local Alignment Search Tool; a sequence comparison algorithm, optimized for speed, used to search sequence databases for regions of local similarity between sequences. The program compares nucleotide or protein sequences to sequence databases and calculates the statistical significance of matches. </div> </div> </div> <div class="wrap"> <strong> blastocyst </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mass of cells formed around a central cavity; an early stage of development after multiple cleavages in a zygote. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> blastomere </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An individual cell of a blastocyst, formed after multiple cleavages. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> blending inheritance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Early concept of heredity proposing that offspring possess a mixture of the traits from both parents. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> boreal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Area located in northern latitudes, between the tundra and the temperate forest, mostly from 52 degrees N to 66 degrees N. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> bottleneck </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A severe, temporary reduction in population size. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> bottom up control </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Control of a population by available nutrients or food. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> bottom-up forces </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Forces within a community that influence the community from lower to higher trophic <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> branch </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Evolutionary connections between organisms in a phylogenetic tree. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> branch migration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Movement of a cross bridge along two DNA molecules. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> branch point </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Adenine nucleotide in nuclear pre-mRNA introns that lies from 18 to 40 nucleotides upstream of the 3' splice site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> breeding value </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The effect of an individual's genes on the value of a given trait in its offspring; sometimes called the additive genotype. It is equal to two times the deviation of the mean of the individual's offspring from the overall population mean. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> broad-sense heritability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proportion of the phenotypic variance that can be attributed to genetic variance. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="C"><div class="padleft10px fleft bold px15">C</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> C value </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Amount of DNA contained in a haploid nucleus; usually a picogram measurement. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> c-Fos </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the Fos family of transcription factors, expressed downstream from signal transduction; identified as proto-oncogene. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> C-value paradox </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The lack of correlation between the DNA content of eukaryotic genomes and a given organism's phenotypic complexity (i.e., the genome of a less complex eukaryotic organism, such as a plant, may contain far more DNA than that of a more complex organism, such as a human being). The paradox is explained by the amount of noncoding repetitive DNA sequences in a genome. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> cache </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stores of food made by many species of animals for future consumption. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/caenorhabditis-elegans-c-elegans-212">Caenorhabditis elegans</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A model eukaryotic, multicellular organism. C. elegans is a nematode that serves as a valuable model to study basic developmental processes, neurological function, and cell communication. </div> </div> </div> <div class="wrap"> <strong> calcitonin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An example of multiple different polypeptides being generated by alternative splicing from the same gene. Different tissues express the different transcripts. For example, calcitonin is more prevalent in the thyroid, while CGRP is highly expressed in brain tissue. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> canalization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The evolution of internal factors during development that reduce the effect of perturbing environmental and genetic influences, thereby constraining variation and consistently producing a particular (usually wild-type) phenotype. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/cancer-272">cancer</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of disease caused by uncontrolled cell division; can exist in many forms. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> candidate gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene thought to be involved in the evolution of a particular trait based on its mutant phenotype or the function of the protein it encodes. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> candidate gene approach </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A technique which attempts to determine if genes of known function affect complex phenotypic traits. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> carcinogen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any substance that causes cancer or aggravates tumors; a substance that damages the genome or metabolism of a cell resulting in uncontrolled cell division. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> caretaker gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A tumor suppressor gene that protects the genome from damage or mutations; usually encodes proteins that recognize or repair DNA damage. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> carnivore </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An animal that eats other animals. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> carnivorous interactions </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species interactions in which one organism eats another organism. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> carrier organism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An individual whose genotype includes a deleterious allele that is not expressed or evident in the phenotype, yet can pass this allele onto offspring ; the individual is "carrying" that allele to a subsequent generation. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> carrying capacity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The population density that can be sustained by limiting resources. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> carrying capacity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The maximum population of a species that a particular ecosystem can sustain. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> case-control study </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An epidemiological method that involves pairing observations of diseased or affected individuals, cases, with matched controls that are as much like the cases but without the disease. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> caspase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme that cleaves other proteins and regulates apoptosis. Each caspase is synthesized as a large, inactive precursor (a procaspase) that is activated by cleavage, often by another caspase. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> caste </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of individuals that are socially distinct from others in the population, and engage in specialized behavior within a specific social group. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> catabolite activator protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that functions in catabolite repression. When bound with cAMP, CAP binds to the promoter of certain operons and stimulates transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/catabolite-repression-113">catabolite repression</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> System of gene control in some bacterial operons in which glucose is used preferentially and the metabolism of other sugars is repressed in the presence of glucose. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> catkins </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small inconspicuous strings of reproductive parts. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> causal variance components </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In a sibling analysis, the portions of phenotypic variance that are due to the underlying genetic and environmental sources of variance (e.g., additive genetic variance, dominance variance, environmental variance). <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> CCCTC binding factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A transcriptional regulator that plays important roles in epigenetic control of gene expression. CTCF is a zinc finger protein that is known for transcriptional insulation. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> cDNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any DNA molecule that is the complementary sequence of an mRNA, typically created synthetically using reverse transcriptase; when labeled and collected in sets, usually reflects the expression profile of a cell or tissue. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cDNA library </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Collection of bacterial colonies or phage colonies containing DNA fragments that have been produced by reverse transcription of cellular mRNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/cell-93">cell</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A single fundamental unit of organisms, the most basic unit of tissues. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cell culture </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The treatment of cells removed from an organism, and sustained in an artificial environment that simulates the condition of the tissue the cells came from; the process of maintaining or multiplying cells in a nutrient solution, and at an optimal temperature, under incubation. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cell cycle </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stages through which a cell passes from one cell division to the next. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cell determination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process during cell maturation or development wherein it becomes committed to a particular cell type; the overall process toward the endpoint of cell differentiation. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cell line </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetically identical cells that divide indefinitely and can be cultured in the laboratory. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cell theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> States that all life is composed of cells, that cells arise only from other cells, and that the cell is the fundamental unit of structure and function in living organisms. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cellular immunity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of immunity resulting from T cells, which recognize antigens found on the surfaces of self cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> centimorgan </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> cM; A unit for measuring distance on a genetic map. One cM is reflects a 1% recombination rate (i.e., c = 0.01). Named after Thomas Hunt Morgan. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> central dogma </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Concept that genetic information passes from DNA to RNA to protein in a one-way information pathway. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> centriole </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cytoplasmic organelle consisting of microtubules; present at each pole of the spindle apparatus in animal cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/centromere-46">centromere</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Constricted region on a chromosome that stains less strongly than the rest of the chromosome; region where spindle microtubules attach to a chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> centromeric sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA sequence found in functional centromeres. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> centrosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Structure from which the spindle apparatus develops; contains the centriole. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cephalization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process over the evolutionary history or development of an organism characterized by a centralization of nervous tissue and nervous system control in the anterior part of the body. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> chaos theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of iterative non-linear systems in which arbitrarily small variations in initial conditions become magnified over time <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> chaperone protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein that helps another protein fold and keeps it stable when not in use, yet is not involved in normal function of that protein. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> character displacement </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Usually refers to a pattern of geographic variation in which a character differs more greatly between sympatric than between allopatric populations of two species; sometimes used for the evolutionary process of accentuation of differences between sympatric populations of two species as a result of the reproductive or ecological interactions between them. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> character state </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the variant conditions of a character (e.g., yellow versus brown as state of the character .color of snail shell.). <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A feature or trait. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Chargaff's rules </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Rules developed by Erwin Chargaff and his colleagues concerning the ratios of bases in DNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> checkpoint </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A key transition point at which progression to the next stage in the cell cycle is regulated. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chemoautotrophs </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that obtain energy through chemical reactions and build biomass directly from inorganic carbon. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> chemosynthetic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The synthesis of organic compounds within an organism, with chemical reactions providing the energy source. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chi-square-test-goodness-of-fit-chi-262">chi square test</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A statistical test that allows one to determine whether observed quantities of a specific characteristic differed from the expected value purely by chance. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> chiasma </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Point of contact between paired (homologous) chromosomes at which crossing over takes place, during the first metaphase of meiosis. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> chimeric oligonucleotide </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An oligonucleotide with a backbone that is composed of subunits with different backbone structures. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ChIP on ChIP assay </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method that combines chromatin immunoprecipitation and DNA microarray analysis to analyze protein-DNA interactions across the genome. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> chloramphenicol acetyl transferase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzyme in bacteria that acetylates chloramphenicol, rendering it inactive in bacterial cells. In molecular biology, it is often used as a reporter to measure gene expression. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> chloroplast </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organelle inside a cell that is responsible for photosynthesis. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> chloroplast DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA in chloroplasts; has many characteristics in common with eubacterial DNA and typically consists of a circular molecule that lacks histone proteins and encodes some of the rRNAs, tRNAs, and proteins found in chloroplasts. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chloroplasts </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The organelle in plant cells in which photosynthesis occurs. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> chorionic villus sampling </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Procedure used for prenatal genetic testing in which a small piece of the chorion (the outer layer of the placenta) is removed from a pregnant woman. A catheter is inserted through the vagina and cervix into the uterus. Suction is then applied to remove the sample. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chromatid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A single, long DNA molecule and its associated proteins, forming half of a replicated chromosome. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chromatin-182">chromatin</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chromatin-immunoprecipitation-chip-153">chromatin immunoprecipitation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An assay used in biology to identify proteins, such as transcription factors, that bind to a specific piece of chromatin in vivo. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chromatin-remodeling-histone-modification-224">chromatin remodeling</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Adding or removing chemical groups to or from histones, which can alter gene expression. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> chromatin-remodeling complex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Complex of proteins that alters chromatin structure without acetylating histone proteins. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chromatin-remodeling protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Binds to a DNA sequence and disrupts chromatin structure, causing the DNA to become more accessible to RNA polymerase and other proteins. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chromosomal-abnormality-39">chromosomal abnormality</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any change in the total number of chromosomes or the physical structure of a chromosome. </div> </div> </div> <div class="wrap"> <strong> chromosomal puff </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Localized swelling of a polytene chromosome; a region of chromatin in which DNA has unwound and is undergoing transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chromosomal rearrangements </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A class of mutations in which whole segments of chromosomes are involved, including inversions and translocations. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> chromosomal scaffold protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that plays a role in the folding and packing of the chromosome, revealed when chromatin is treated with a concentrated salt solution, which removes histones and some other chromosomal proteins. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chromosome-chromosomes-eukaryotic-chromosome-eucariotic-chromosome-procariotic-6">chromosome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A chromosome is a single, long molecule of DNA. Chromosomes are highly organized structures that store genetic information in living organisms </div> </div> </div> <div class="wrap"> <strong> chromosome deletion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Loss of a chromosome segment. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chromosome duplication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mutation that doubles a segment of a chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chromosome inversion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A 180-degree reversal of the orientation of a part of a chromosome, relative to some standard chromosome. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chromosome-map-105">chromosome map</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Representation of the physical location of genes on a chromosome, generally derived from studies looking at recombination rates between known loci. </div> </div> </div> <div class="wrap"> <strong> chromosome mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Difference from the wild type in the number or structure of one or more chromosomes; often affects many genes and has large phenotypic effects. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chromosome painting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Visualization of individual, whole chromosomes by fluorescence in situ hybridization (FISH). </div> </div> </div> <div class="wrap"> <strong> chromosome rearrangement </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Change from the wild type in the structure of one or more chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chromosome-territories-34">chromosome territories</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The areas of the nucleus in which particular chromosomes reside. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/chromosome-theory-of-inheritance-chromosome-theory-chromosome-127">chromosome theory of inheritance</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An accepted theory that chromosomes are the material of inheritance, and that they are associated in paternal-maternal pairings; dervied from the collective work of Boveri, Sutton, and Morgan. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> chromosome walking </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method of locating a gene by using partly overlapping genomic clones to move in steps from a previously cloned, linked gene to the gene of interest. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> chronosequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Predictable change of vegetation over time. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> chronosequence method </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Used to infer succession by replacing a successional stage by spatial differences in time since an initial community state. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> chronospecies </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A segment of an evolving lineage preserved in the fossil record that differs enough from earlier or later members of the lineage to be given a different binomial (name). Not equivalent to biological species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> cis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> cis-acting elements affect only loci on the same strand of DNA </div> </div> </div> <div class="wrap"> <strong> cis configuration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Arrangement in which two or more wild-type genes are on one chromosome and their mutant alleles are on the homologous chromosome; also called coupling configuration. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/cis-regulatory-element-cis-regulatory-element-75">cis-regulatory element</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A noncoding DNA sequence in or near a gene required for proper spatiotemporal expression of that gene, often containing binding sites for transcription factors. Often used interchangeably with enhancer. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/clade-269">clade</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The set of species descended from a particular ancestral species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> cladistic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pertaining to branching patterns; a cladistic classification classifies organisms on the basis of the historical sequences by which they have diverged from common ancestors. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> cladogenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Branching of lineages during phylogeny. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> cladogram </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cladogram is an evolutionary tree that diagrams evolutionary relationships among organisms; branch points show different relationships in time; distinct from a phylogenetic tree branch points which show departure from common traits (derived traits), and common ancestors. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cleavage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The series of mitotic cell divisions that produce a blastocyst from a zygote. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> climate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The long-term prevailing weather in an area that is largely determined by temperature and precipitation. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> climate change </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Changes in global climate patterns attributed to increased levels of carbon dioxide in the atmosphere as well as changes in average global temperature. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> climax community </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A community composed of species that represents the final stage of colonization of a habitat. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> cline </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gradual change in an allele frequency or in the mean of a character over a geographic transect. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> clinical trial </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process by which new drugs are tested in humans; involve multiple stages and rounds (stage I-III); results are used for seeking approval from government agencies that permit drugs to be sold to the public. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> clonal evolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process by which mutations that enhance the ability of cells to proliferate predominate in a clone of cells, allowing the clone to become increasingly rapid in growth and increasingly aggressive in proliferation properties. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> clone </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A single organism, or a lineage of individual organisms that have reproduced asexually, by mitotic division. Can occur naturally or by synthetic manipulation of reproductive cells. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cloning strategy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Particular set of methods used to clone a gene or DNA fragment. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cloning vector </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stable, replicating DNA molecule to which a foreign DNA fragment can be attached and transferred to a host cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cloverleaf structure </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Secondary structure common to all tRNAs. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> co-accumulation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Simultaneous accumulation of more than one element by plants. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> co-option </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The evolution of a function for a gene, tissue, or structure other than the one it was originally adapted for. At the gene level, used interchangeably with recruitment and, occasionally, exaptation. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> coactivator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that cooperates with an activator of transcription. In eukaryotic transcriptional control, coactivators often physically interact with transcriptional activators and the basal transcription apparatus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> coadapted gene pool </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A population or set of populations in which prevalent genotypes are composed of alleles at two or more loci that confer high fitness in combination with each other, but not with alleles that are prevalent in other such populations. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> coalescence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Derivation of the gene copies in one or more populations from a single ancestral copy, viewed retrospectively (from the present back into the past). <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> coding exons of genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A sequence of DNA that is transcribed to messenger RNA and codes information for protein synthesis. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> coding strand </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The side of the double helix for a particular gene from which RNA is not transcribed. </div> </div> </div> <div class="wrap"> <strong> codominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of allelic interaction in which the heterozygote simultaneously expresses traits of both homozygotes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> codominant marker </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genetic marker in which the heterozygotes can be distinguished from both homozygotes. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/codon-155">codon</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A triplet sequence of DNA or RNA nucleotides corresponding to a specific amino acid or a start/stop signal in translation. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> coefficient of coincidence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Ratio of observed double crossovers to expected double crossovers. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> coefficient of relatedness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The proportion of genes identical by descent (IBD) among two individuals I and J. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> coevolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The influence that two ecologically-interacting species have on each other, wherein each species responds to selection imposed by the other; a history of joint divergence of ecologically associated species. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cofactor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A term for any substance that necessary for optimal activity of an enzyme. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cognition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Brain function involving memory, decision making, and temporal awareness; problem solving capacity of the brain. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cohesin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Molecule that holds the two sister chromatids of a chromosome together. The breakdown of cohesin at the centromeres enables the chromatids to separate in anaphase of mitosis and anaphase II of meiosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cohesive end </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Short, single-stranded overhanging end on a DNA molecule produced when the DNA is cut by certain restriction enzymes. Cohesive ends are complementary and can spontaneously pair to rejoin DNA fragments that have been cut with the same restriction enzyme. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cointegrate structure </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Produced in replicative transposition, an intermediate structure in which two DNA molecules with two copies of the transposable element are fused. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> coisogenic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Two strains that are genetically identical (i.e., isogenic), except for a single locus. This occurs most often by a spontaneous mutation by many generations of backcrossing. Coisogenic strains are also becoming available due to target mutagenesis (knockouts) in embryonic stem (ES) cells. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> colinearity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In molecular biology, the concept that there is a direct correspondence between the linear order of a nucleotide sequence of a gene and the continuous sequence of amino acids in a protein. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Combined DNA Index System (CODIS) </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A DNA database used in forensic analysis in the United States; a distributed database organized into three hierarchical levels, local, state, and national, and stores indexed and searchable digitized representations of DNA samples. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> commensalism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An ecological relationship between species in which one is benefited but the other is little affected. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> commitment to differentiation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The notion that a cell has irreversibly initiated a series of transcriptional events that results in a change in various aspects of cell physiology, such as size, shape, polarity, metabolism, signal transduction, and gene expression profiles. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> common garden </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A place in which (usually conspecific) organisms, perhaps from different geographic populations, are reared together, enabling the investigator to ascribe variation among them to genetic rather than environmental differences. Originally applied to plants, but now more generally used to describe any experiment of this design. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> common garden experiment </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An experimental design in which individuals from multiple populations are raised together in the same environment in order to test for genetic differentiation in phenotypic traits. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> community assembly </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> How species are added to and lost from communities, and how communities change over time. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> community assembly theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Theory suggesting that similar sites can develop different biological communities depending on order of arrival of different species.Â  <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> community ecology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of how resource availability influences ecosystem characteristics, including the number and types of species present. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/comparative-genomic-hybridization-cgh-56">comparative genomic hybridization</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A molecular cytogenetic method of screening cells for DNA gains and losses at a chromosomal level. Differentially labelled test and reference DNA are hybridized simultaneously to metaphase chromosomes to generate a map of DNA copy number changes. <div class="px10">Nature Reviews Cancer</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/comparative-genomics-165">comparative genomics</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The evaluation of similarities and differences between genomes of different organisms; can reveal differences between individuals and species as well as evolutionary relationships. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> comparative method </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A procedure for inferring the adaptive function of a character by correlating its states in various taxa with one or more variables, such as ecological factors hypothesized to affect its evolution. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> compartment </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A contiguous group of cells, descended from the same progenitor cell, that form a spatially discrete part of a developing organ or structure and often act as a discrete developmental unit. Cells from one compartment typically do not intermix with cells from other compartments. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> compensatory mutations </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutation that ameliorates the deleterious fitness effects of another mutation. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> competent cell </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Capable of taking up DNA from its environment (capable of being transformed). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> competition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An interaction between individuals of the same species or different species whereby resources used by one are made unavailable to others. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> competition exclusion principles </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Principle stating that no two species competing for the same resource can coexist indefinitely. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> competitive exclusion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Extinction of a population due to competition with another species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> complementary </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the relation between the two nucleotide strands of DNA in which each purine on one strand pairs with a specific pyrimidine on the opposite strand (A pairs with T, and G pairs with C). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> complementation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Two different mutations in the heterozygous condition are exhibited as the wild-type phenotype; indicates that the mutations are at different loci. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> complementation test </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Test designed to determine whether two different mutations are at the same locus (are allelic) or at different loci (are nonallelic). Two individuals that are homozygous for two independently derived mutations are crossed, producing F1 progeny that are heterozygous for the mutations. If the mutations are at the same locus, the F1 will have a mutant phenotype. If the mutations are at different loci, the F1 will have a wild-type phenotype. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> complete dominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Exists when the phenotype of a heterozygote is identical to that of a homozygous dominant individual. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/complete-linkage-133">complete linkage</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Linkage between genes that are located close together on the same chromosome with no crossing over between them. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> complex disease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A pathological condition of the body that is the result of defects in a number of genetic and environmental factors. These conditions do not follow Mendelian inheritance patterns. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> complex life cycle </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A term coined by HM Wilbur in 1980 referring to a life cycle wherein an organism changes form, physiology and behavior, as well as habitat; also called CLC. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/complex-trait-82">complex trait</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait that does not follow Mendelian Inheritance patterns, is likely dervied from multiple genes, and exhibits a large variety of phenotypes. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> composite transposon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of transposable element in bacteria that consists of two insertion sequences flanking a segment of DNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> compound chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fusion of two separate chromosomes. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> compound heterozygote </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An individual organism that possesses two different mutant alleles at a locus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> concept of dominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The idea proposed by Mendel to explain an observed phenomenon of heredity, wherein two different alleles are present in a genotype, and only one allele is expressed in the phenotype. The expression of that allele is considered to dominate the unexpressed allele. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> concerted evolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Maintenance of a homogeneous nucleotide sequence among the members of a gene family, which evolves over time. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> concordance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Percentage of twin pairs in which both twins have a particular trait. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> concordant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a pair of twins both of whom have the trait under consideration. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> conditional mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Expressed only under certain conditions. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> confidentiality </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The idea that private information about an individual will not be shared with others. </div> </div> </div> <div class="wrap"> <strong> configuration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to almost limitless aspects of landscape heterogeneity, especially the physical and spatial distribution of landscape elements. Configuration metrics that apply across an entire landscape would include characteristics such as the dendritic pattern of streams in a watershed, random or regular distribution of patches, and diversity of habitat types. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> conformation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The spatial arrangement, folding or shape of a macromolecule, such as a protein or nucleic acid. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> congenic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that are almost genetically identical; ideally, they differ at only one locus. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> congenic strain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An inbred strain of animals that are continually interbred. Generally, it takes 10 generations of crossing two inbred lines to create a congenic line that differs in only one locus. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> congenital </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A condition that is present at birth. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> conjugation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mechanism by which genetic material may be exchanged between bacterial cells. During conjugation, two bacteria lie close together and a cytoplasmic connection forms between them. A plasmid or sometimes a part of the bacterial chromosome passes through this connection from one cell to the other. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/conjugation-prokaryotes-290">conjugation (prokaryotes)</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Conjugation is a process by which one bacterium transfers genetic material to another through direct contact </div> </div> </div> <div class="wrap"> <strong> connective tissue </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Connective tissue is the material inside your body that supports many of its parts. It is the cellular glue that gives your tissues their shape and helps keep them strong. It also helps some of your tissues do their work. Cartilage and fat are examples of connective tissue. <div class="px10">http://www.nlm.nih.gov/medlineplus/</div> </div> </div> </div> <div class="wrap"> <strong> connectives </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Strains of organisms developed by backcrossing the nuclear genome from one strain into the cytoplasm of another; the mitochondrial parent is always the female parent during the backcrossing program. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> consanguinity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Relation by descent from a common ancestor. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/consensus-sequence-220">consensus sequence</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Comprises the most commonly encountered nucleotides found at a specific location in DNA or RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> conseration biology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A multidisciplinary science that has developed to address the loss of biological diversity. Conservation biology has two central goals: to evaluate human impacts on biological diversity, and to develop practical approaches to prevent the extinction of species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> consomic strain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that are produced by repeated backcrossing of a whole chromosome such as the X or Y chromosome onto an inbred strain. As with congenic strains, a minimum of 10 backcross generations is required. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> conspecific </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Belonging to the same species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> conspecifics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Belonging to the same species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> constitutive mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Causes the continuous transcription of one or more structural genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> consumers </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that get their energy from eating primary producers. A rabbit is a consumer that eats grasses. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> contig </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Set of overlapping DNA fragments that have been assembled in the correct order to form a continuous stretch of DNA sequence. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> continental islands </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Islands which have broken off from a mainland. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> continuous characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Displays a large number of possible phenotypes that are not easily distinguished, such as human height. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> continuous replication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Replication of the leading strand in the same direction as that of unwinding, allowing new nucleotides to be added continuously to the 3' end of the new strand as the template is exposed. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> convergent evolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Evolution of similar features independently in different evolutionary lineages, usually from different antecedent features or by different developmental pathways. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> cooperation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An association between individuals or groups that benefits all involved. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cooperative breeding </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When (typically) non-breeding auxiliaries, or helpers, raise others. offspring. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> coordinate induction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Simultaneous synthesis of several enzymes that is stimulated by a single environmental factor. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/copy-number-variation-cnv-55">copy number variation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When the number of copies of a particular genetic sequence is different between individuals. </div> </div> </div> <div class="wrap"> <strong> core element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consensus sequence in eukaryotic RNA polymerase I promoters that extends from -45 to -20 and is needed to initiate transcription; rich in guanine and cytosine nucleotides. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> core enzyme </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Part of bacterial RNA polymerase that, during transcription, catalyzes the elongation of the RNA molecule by the addition of RNA nucleotides; consists of four subunits: two copies of alpha (.), a single copy of beta (.), and a single copy of beta prime (.'). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> core promoter </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Located immediately upstream of eukaryotic promoter, DNA sequences to which the basal transcription apparatus binds. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> corepressor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Substance that inhibits transcription in a repressible system of gene regulation; usually a small molecule that binds to a repressor protein and alters it so that the repressor is able to bind to DNA and inhibit transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> correlated response to selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An evolutionary change in an unselected trait caused by an additive genetic correlation between the unselected trait and a trait under selection. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> correlation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Degree of association between two or more variables. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> correlation coefficient </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Statistic that measures the degree of association between two or more variables. A correlation coefficient can range from -1 to +1. A positive value indicates a direct relation between the variables; a negative correlation indicates an inverse relation. The absolute value of the correlation coefficient provides information about the strength of association between the variables. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> correlational selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of selection in which two traits interact nonadditively to determine fitness, characterized by the finding that certain combinations of trait values have higher fitness than other combinations. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> corridors </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Relatively narrow, linear strips of habitat between otherwise isolated habitat patches. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> cosmid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cloning vector that combines the properties of plasmids and phage vectors and is used to clone large pieces of DNA in bacteria. Cosmids are small plasmids that carry . cos sites, allowing the plasmid to be packaged into viral coats. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cost benefit ratio </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ratio of the cost of an act to its benefit, measured in terms of evolutionary fitness. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> cost of resistance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The fitness effects of an allele that confers resistance (often denoted by R) to a pesticide or antibiotic in the absence of the pesticide or antibiotic. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> cotransduction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process in which two or more genes are transferred together from one bacterial cell to another. Only genes located close together on a bacterial chromosome will be cotransduced. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cotransformation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process in which two or more genes are transferred together during cell transformation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> covariance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of how much two variables change together. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> CpG island </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA region that contains many copies of a cytosine base followed by a guanine base; often found near transcription start sites in eukaryotic DNA. The cytosine bases in CpG islands are commonly methylated when genes are inactive but are demethylated before the initiation of transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/cri-du-chat-263">cri du chat</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A human genetically-based defect resulting from a partial deletion on chromosome 5; affected infants exhibit a cry that is cat-like, as well as cognitive and physical limitations. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> critical period </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A window of time during an individual's development when a function or tissue structure is most vulnerable to external variables and intervention that has permanent effects. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cross bridge </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In a heteroduplex DNA molecule, the point at which each nucleotide strand passes from one DNA molecule to the other. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cross resistance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The condition in which resistance to one pesticide or antibiotic confers increased resistance to a second pesticide or antibiotic. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> cross-fostering </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An experimental technique in which offspring are reared (fostered) by animals other than their genetic parents; cross-fostering is designed to reduce parental effects. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> crossing over </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> During meiosis, the exchange of genetic material between chromatids. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cruciform </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Structure formed by the pairing of inverted repeats on both strands of double-stranded DNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> crypsis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Defense of prey species through a shape or coloration that provides camouflage from predators. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> cryptic choice </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Post-copulatory female choice is the ability of females to affect the likelihood that sperm from a particular male fertilizes their eggs, and their decision to invest in offspring based on the identity of the male with whom they mate; this choice is made via morphological, chemical and behavioral adaptations that happens inside the female reproductive tract and cannot be detected from behavioral studies alone. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> cyanobacteria </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A kind of bacteria that are aquatic and photosynthetic; exist today, and also identified in fossils more than 3.5 billion years old. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cyanobacterial </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Relating to or caused by the the photosynthetic organism cyanobacteria. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cyclic AMP </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A second messenger formed from ATP that is involved in signal transduction, generally translating hormonal signals to the nucleus. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> cyclic AMP response element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An element, or sequence, in DNA found in genes whose transcription is induced by cAMP. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> cyclic AMP response element binding transcription factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein that is activated by cAMP and subsequently phosphorylated by protein kinase A. It then binds to cAMP response elements in certain genes to initiate their transcription. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> cyclin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A key protein in the control of the cell cycle; combines with a cyclin-dependent kinase (CDK). The levels of cyclin rise and fall in the course of the cell cycle. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cyclin-dependent kinase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A key protein in the control of the cell cycle; combines with cyclin. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/cytogenetics-72">cytogenetics</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of chromosomal structure and function and how they are inherited. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cytokine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A potent immunomodulator that is secreted by an immune cell and affects host response to infection or tissue trauma; can be a protein or glyocoprotein; examples are interleukins or interferons. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/cytokinesis-100">cytokinesis</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cytokinesis is the physical process of cell division that divides the cytoplasm of a parent cell into two daughter cells </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/cytoplasm-280">cytoplasm</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The thick solution of the cell body where organelles and other cellular components are housed; a collection of aqueous molecules and macromolecules that fills each cell and is enclosed by the cell membrane, but not present in the nucleus; mainly composed of water, salts and proteins. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cytoplasmic inheritance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Inheritance of characteristics encoded by genes located in the cytoplasm. Because the cytoplasm is usually contributed entirely by only one parent, cytoplasmically inherited characteristics are usually inherited from a single parent. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cytoplasmic trait </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait encoded by a gene found in a cytoplasmic organelle. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> cytosine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pyrimidine in DNA and RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> cytosine methylation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The addition of methyl groups to cytosine nucleotides in a DNA molecule. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> cytoskeleton </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The internal structural framework of a cell that contributes to cell shape and movement; composed of microflaments, intermediate filaments, and microtubulues. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> cytosol </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The aqueous component of the cell cytoplasm. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="D"><div class="padleft10px fleft bold px15">D</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> D loop </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Region of mitochondrial DNA that contains an origin of replication and promoters; is displaced during initiation of replication, leading to the name displacement, or D, loop. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> dam methylase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzyme that adds methyl groups to specific sites in DNA, inhibiting transcription from these sites. </div> </div> </div> <div class="wrap"> <strong> dams </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The female parents in a quantitative genetic breeding experiment. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/danio-rerio-zebrafish-170">Danio rerio</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The Latin name for zebrafish, a commonly used model organism. </div> </div> </div> <div class="wrap"> <strong> deamination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Loss of an amino group (NH2) from a base. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> dedifferentiated </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cell less specialized than the cell it descended from, such as a cancer cell. </div> </div> </div> <div class="wrap"> <strong> degenerate code </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the fact that the genetic code contains more information than is needed to specify all 20 common amino acids. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> deletion mapping </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Technique for determining the chromosomal location of a gene by studying the association of its phenotype or product with particular chromosome deletions. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> deletion mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of mutation in a DNA sequence involving the removal of one or more nucleotides. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> deletion stock </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A line of Drosophila that has a piece of a chromosome missing from its genome. </div> </div> </div> <div class="wrap"> <strong> delta sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Long terminal repeat in Ty elements of yeast. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> deme </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A local interbreeding unit within a metapopulation. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> demographic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pertaining to processes that change the size of a population (i.e., birth, death, dispersal). <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> demography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of statistics relating to birth and deaths in populations. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> denaturation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process that separates the strands of doublestranded DNA when DNA is heated. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> denitrification </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process facilitated by bacteria, in which nitrates (NO3) break down to molecular nitrogen (N2). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> density dependence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The performance of individuals in a population depends on how many individuals are in that population. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> density dependent selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Selection that differs according to population density. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> density-dependent </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Affected by population density. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> deoxyribocleotide </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Basic building block of DNA, consisting of a deoxyribose sugar, a phosphate, and a nitrogenous base. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> deoxyribonuclease I </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzyme that makes single-stranded nicks in DNA. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> deoxyribonucleic acid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The primary molecule of inheritance in nearly all organisms; a double-stranded polymer of nucleotides that contains the sugar deoxyribose; abbreviated as DNA. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> deoxyribose sugar </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Five-carbon sugar in DNA; lacks a hydroxyl group on the 2'-carbon atom. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> depurination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Break in the covalent bond connecting a purine base to the 1'-carbon atom of the deoxyribose sugar, resulting in the loss of the purine base. The resulting apurinic site cannot provide a template in replication, and a nucleotide with another base may be incorporated into the newly synthesized DNA strand opposite the apurinic site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> derived character </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A character (or character state) that has evolved from an antecedent (ancestral) character or state. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> deterministic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Causing a fixed outcome, given initial conditions. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> deterrence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The degree to which a plant defense is able to reduce damage during a choice test (in which a natural enemy is able to choose between defended and undefended plants). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> diakinesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fifth substage of prophase I in meiosis. In diakinesis, chromosomes contract, the nuclear membrane breaks down, and the spindle forms. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> dicentric bridge </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Structure produced when the two centromeres of a dicentric chromatid are pulled toward opposite poles, stretching the dicentric chromosome across the center of the nucleus. Eventually, the dicentric bridge breaks as the two centromeres are pulled apart. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> dicentric chromatid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromatid that has two centromeres; produced when crossing over takes place within a paracentric inversion. The two centromeres of the dicentric chromatid are frequently pulled toward opposite poles in mitosis or meiosis, breaking the chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Dicer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A ribonuclease that cleaves double-stranded RNA molecules into fragments approximately 20 to 25 nucleotides long that ultimately interfere with the expression of the corresponding gene. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> dideoxyribonucleoside triphosphate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Special substrate for DNA synthesis used in the Sanger dideoxy sequencing method; identical with dNTP (the usual substrate for DNA synthesis) except that it lacks a 3'-OH group. The incorporation of a ddNTP into DNA terminates DNA synthesis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> diethylstilbestrol </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A synthetic nonsteroidal estrogen that was found to cause birth defects in pregnant women. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> differential gene expression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Differences in the time, location, and/or quantitative level at which a gene expresses the protein it encodes. Differential gene expression involves differences between species, developmental stages, or physiological states in the specific cells, tissues, structures, or body segments that express a given gene; it is believed to be a significant agent of morphological change over evolutionary time. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/differentiation-134">differentiation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The acquisition of cell-specific differences during a multicellular organism's embryonic development or adult life; reflects gene expression and activation of transcription factors. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/dihybrid-cross-dihybrid-303">dihybrid cross</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A dihybrid cross describes a mating experiment between two organisms that are identically hybrid for two traits </div> </div> </div> <div class="wrap"> <strong> dioecious </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a species with male and female reproductive structures in separate individuals. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/diploid-310">diploid</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a cell that contains two copies of each chromosome. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> diploid cell </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cell containing two copies (one from each parent) of chromosomes. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> diplotene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fourth substage of prophase I in meiosis. In diplotene, centromeres of homologous chromosomes move apart, but the homologs remain attached at chiasmata. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> direct benefits </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Benefits gained by females from their choice of mate and that directly affect her survival and/or fecundity. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> direct development </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A life history in which the intermediate larval stage is omitted and development proceeds directly from an embryonic form to an adult-like form. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> direct fitness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Reproductive success through one.s own offspring. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> direct repair </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA repair in which modified bases are changed back to their original structures. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> direct selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The type of selection in which there is a causal relationship between a phenotypic trait and fitness, which can result in adaptation. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> direct transmission </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Movement of a parasite from one host to another of the same species without an intermediate organism. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> directional selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Over time, the change in the mean value of a character in a population that is either higher or lower than its current mean value, resulting in a shift in the plot of trait frequency. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> discontinuous characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Exhibits only a few, easily distinguished phenotypes. An example is seed shape in which seeds are either round or wrinkled. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> discontinuous replication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Replication of the lagging strand in the direction opposite that of unwinding, which means that DNA must be synthesized in short stretches (Okazaki fragments). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> discordant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a pair of twins of whom one twin has the trait under consideration and the other does not. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> discrete generations </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A life history, like that of an annual plant, in which the parental generation has died by the time the offspring generation reproduces. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> discrete polymorphism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A phenotypic trait that exhibits only a few (usually two or three) distinct types or morphs. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/disease-37">disease</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A pathological condition of the body that results in abnormal functioning of an organ or organ system. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> disomy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes the state of cell that has two members of a pair of homologous chromosomes. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> dispersal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In population biology, movement of individual organisms to different localities; in biogeography, extension of the geographic range of a species by movement of individuals. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> disperse </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> To spread widely. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> displaced chromosome duplication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Duplication of a chromosome segment in which the duplicated segment is some distance from the original segment. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> displacement behavior </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Grooming, touching, or scratching which occurs when an animal is faced with conflicting behavioral needs, or is placed in a circumstance where it cannot express the behavior it is motivated to perform. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> disruptive selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In a population over time, a type of selection that favors phenotypic extremes. <div class="px10">©Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> disturbance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any process that removes biomass from the community; an abiotic event, natural or human-caused such as fires and storms, that kills or damages some organisms and thereby creates opportunities for other organisms to grow and reproduce. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> disturbance events </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Variation in climate, variation in flooding frequency or drought frequency, or frequencies of storm events characterized by their frequency and impact. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> disturbed habitat species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species that often live where avalanches, mud slides, and fires occur frequently. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> diurnal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An animal who is active during the day and sleeps at night. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/divergence-196">divergence</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The evolution of increasing difference between lineages in one or more characters. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> diversification </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An evolutionary increase in the number of species in a clade, usually accompanied by divergence in phenotypic characters. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> diversifying selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> See disruptive selection. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> dizygotic twins </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Nonidentical twins that arise when two different eggs are fertilized by two different sperm; also called fraternal twins. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/dna-deoxyribonucleic-acid-107">DNA</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Deoxyribonucleic acid, the primary molecule of inheritance in nearly all organisms; a double-stranded polymer of nucleotides that contains the sugar deoxyribose. <div class="px10">Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> DNA backbone </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The component of DNA strands composed of deoxyribose sugar and phosphate; main structure to which nucleotides attach to create a sequence template. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> DNA binding domain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A general term for a single- or double-stranded region of DNA for which a specific protein has an affinity to bind. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/dna-fingerprinting-185">DNA fingerprinting</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Technique used to identify individuals by examining their DNA sequences. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA footprinting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Technique used to determine which DNA sequences are bound by a protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA forensics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A field of science that uses DNA evidence to assist in the solving of crimes. </div> </div> </div> <div class="wrap"> <strong> DNA gyrase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> E. coli topoisomerase enzyme that relieves torsional strain that builds up ahead of the replication fork. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA helicase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that unwinds double-stranded DNA by breaking hydrogen bonds. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA library </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Collection of bacterial colonies containing all the DNA fragments from one source. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA ligase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme that catalyzes the formation of a phosphodiester bond between adjacent 3_-OH and 5_-phosphate groups in a DNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA methylation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A heritable chemical change to DNA involving a methyl group attaching to DNA; the accumulation is a form of epigenetic control of gene expression. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/dna-polymerase-dnap-1">DNA polymerase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzyme that catalyzes the synthesis of new DNA. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> DNA polymerase I </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial DNA polymerase that removes and replaces RNA primers with DNA nucleotides. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA polymerase II </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial DNA polymerase that takes part in DNA repair; restarts replication after synthesis has halted because of DNA damage. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA polymerase III </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial DNA polymerase that synthesizes new nucleotide strands off the primers. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA polymerase IV </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial DNA polymerase; probably takes part in DNA repair. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA polymerase V </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial DNA polymerase; probably takes part in DNA repair. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNA probe </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A general term for a short sequence of DNA or RNA that has a label attached, so that when applied to a biological sample it will reveal the location of a complementary sequence in that sample. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/dna-repair-161">DNA repair</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any one of many cellular processes that attempts to correct errors in cellular DNA introduced via the environment or during cell division. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/dna-sequencing-205">DNA sequencing</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process of determining the sequence of bases along a DNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> DNase I hypersensitive site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromatin region that becomes sensitive to digestion by the enzyme DNase I. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/dnase-i-sensitivity-dnase-sensitivity-208">DNAse I sensitivity</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method that detects DNA sites in chromosomes that show increased sensitivity to digestion by DNAse I. These sites probably represent regions of the chromosome that are nucleosome-free, and often correspond to gene-control regions. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> domain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In protein chemistry, a protein segment,100 amino acids or less, that can fold into a specific three-dimensional structure independent of other domains on the same protein; in general biology, an organizing principle used to define separate categories of life. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> dominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The extent to which a trait appears in a population or an individual, resulting from allelic interactions. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> dominance genetic variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Component of the genetic variance that can be attributed to dominance (interaction between genes at the same locus). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> dominance variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The magnitude of the phenotypic (and genotypic) variance that is due to dominance, that is, the interaction between alleles at the same locus. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/dominant-81">dominant</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a trait that appears more frequently than another trait, resulting from interactions between gene alleles. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> dominant marker </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A known DNA sequence that generally characterizes an example of variation in a genome, like a mutation, single nucleotide polymorphism, or variable number of tandem repeats. Dominant markers allow for analyzing the DNA in multiple parts across an entire genome. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> dominant species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The most abundant species in a community, exerting a strong influence over the occurrence and distribution of other species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> dosage compensation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Equalization in males and females of the amount of protein produced by X-linked genes. In placental mammals, dosage compensation is accomplished by the random inactivation of one X chromosome in the cells of females. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> double fertilization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fertilization in plants; includes the fusion of a sperm cell with an egg cell to form a zygote and the fusion of a second sperm cell with the polar nuclei to form an endosperm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/double-helix-277">double helix</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The double helix is a description of the molecular shape of a double-stranded DNA molecule. </div> </div> </div> <div class="wrap"> <strong> double-strand-break model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Model of homologous recombination in which a DNA molecule undergoes doublestrand breaks. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> down mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Decreases the rate of transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/down-syndrome-257">Down syndrome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Down syndrome; Characterized by variable degrees of mental retardation, characteristic facial features, some retardation of growth and development, and an increased incidence of heart defects, leukemia, and other abnormalities; caused by the duplication of all or part of chromosome 21 (trisomy 21). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> downstream </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Toward the 3' end of a chain of nucleotides. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> downstream core promoter element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consensus sequence [RG(A or T)CGTG] found in some eukaryotic RNA polymerase II core promoters; usually located approximately 30 bp downstream of the transcription start site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Drosophila melanogaster </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The fruit fly, a commonly used model organism for genetic and development studies. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/drug-101">drug</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A substance that is used in the treatment of disease. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> dryas </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A common plant along the successional chain of species for forests. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> dulotic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A practice of ants in which they force ants of another species to work for their colony; slave-making ants. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> dyad </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A term used to describe a pair; in genetics, a pair of homologous chromosomes after separation from a tetrad (foursome). <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> dynamic mosaic paradigm </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In this paradigm landscapes are viewed as heterogeneous with more continuous variation rather than divided into discrete and distinct habitats. The conceptual emphasis is viewed from the perspective of a particular ecological process or organism. in contrast to the patch-corridor-matrix. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="E"><div class="padleft10px fleft bold px15">E</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> eclose </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When an adult insect emerges from pupal or a larvae emerge from an egg. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecological climax </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A state for communities which represents the final, or permanent end-stage of succession. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ecological community </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of interacting or potentially interacting species that inhabit a particular location at a particular time, with shared environmental influences. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ecological composition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The relative proportion of habitat types in the landscape, regardless of spatial distribution. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ecological drift </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Random change in species abundance over time. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecological facilitation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When one species, or a group of species, colonizes a disturbed area, and subsequently alters the environment of that area, by altering soil nutrients, light accessibility, or water availability. The effect is making the area more habitable for later successional species. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ecological fragmentation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process of breaking a natural landscape into fewer, smaller and more disjointed areas of habitat. Loss of total area and variety of habitats is called change in composition. Change in the variety, spatial arrangement, shape and size of habitats is change in configuration. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecological levels </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The organizational levels at which ecologists study the interactions between organisms and their environment. These levels include individuals, populations, communities, and ecosystems. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecological niche </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The range of combinations of all relevant environmental variables under which a species or population can persist; often more loosely used to describe the .role. of a species, or the resources it utilizes. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> ecological niche/niche </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The particular range of conditions that species. can tolerate, and how their physiological responses impact species. geographic distributions. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecological release </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The expansion of a population's niche (e.g., range of habitats or resources used) where competition with other species is alleviated. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> ecological remediation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process or plan of improving an existing ecosystem or creating a new one by replacing what has deteriorated or been destroyed. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ecological restoration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Efforts to recreate, initiate, or accelerate the recovery of an ecosystem that has been disturbed. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecological succession </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process by which biological community composition, the number and proportion of different species in an ecosystem, recover over time following a disturbance event. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecological tolerance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The specific range of environmental factors, such as light, temperature, and availability of water, within which an organism can survive. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> economic threshhold </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The population density of the potential pest below which the damage to the crop is insignificant (i.e. it is not really necessary to spray). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecosystem ecology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of all organisms living in a particular area as well as the nonliving, physical components with which they interact such as air, soil, water and sunlight. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecosystem services </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Resources and processes provided to humankind by natural ecosystems. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecosytem engineer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organism that creates or modifies habitats in landscape, for example beaver which create ponds and modify wetlands. Plants are important ecosystem engineers, for example altering shading or providing habitat for other organisms. Humans are the most influential ecosystem engineers. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecosytems </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Interacting systems of organisms living in a particular area and the physical environment with which they interact such as air, soil, water and sunlight. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecotones </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transitional zones between two different parts of an ecosystem which often have important influences on ecological processes. An example might be the transitional structure between forest and grassland patches. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecotourism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Travel with the desire to view, sustain, and support natural ecosystems and local cultures. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ecotype </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genetically determined phenotype of a species that is found as a local variant associated with certain ecological conditions. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> ecotypes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Locally adapted populations that are phenotypically and genetically differentiated for adaptive traits. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> ectoderm </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Outer germ layer of an embryo, formed by gastrulation; distinct from endoderm and mesoderm. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ectoparasite </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Parasite that lives and feeds on the outside of body of its host. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ectotherms </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that control body temperature through external means. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> edge effects </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Impacts of one habitat on an adjacent habitat. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Edward syndrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Characterized by severe retardation, low-set ears, a short neck, deformed feet, clenched fingers, heart problems, and other disabilities; results from the presence of three copies of chromosome 18 (trisomy 18). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> effective population size </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The effective size of a real population is equal to the number of individuals in an ideal population (i.e., a population in which all individuals reproduce equally) that produces the rate of genetic drift seen in the real population. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> egg </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Female gamete. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> egg-polarity gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Determines the major axes of development in an early fruit fly embryo. One set of egg-polarity genes determines the anterior-posterior axis and another determines the dorsalventral axis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> el niã‘southern oscillation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A climate pattern that occurs across the tropical Pacific Ocean on average every three to seven years and affects trade winds and ocean currents due to a redistribution of heat. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> electrophoresis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A technique for separating macromolecules (proteins, RNA, DNA) on a gel using an electric field. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> electrophoretic mobility shift assay </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method that examines whether a specific protein binds to a specific piece of DNA. After allowing the DNA and protein to interact in vitro, the complex is electrophoresed, analyzed, and compared to DNA alone versus DNA plus protein. If the protein has bound, the complex will not move as far into the gel due to its larger size. </div> </div> </div> <div class="wrap"> <strong> elevational gradient </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> As one travels to higher elevations, the number of species peaks at mid-elevations or declines. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> elimination sample </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A DNA sample collected from an individual not thought to be a suspect in a crime (such as the partner of a rape victim) to help investigators to analyze the evidence. <div class="px10">Phil Reilly</div> </div> </div> </div> <div class="wrap"> <strong> elongation factor for translation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that facilitates the extension of a growing polypeptide. </div> </div> </div> <div class="wrap"> <strong> elongation factor G (EF-G) </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that combines with GTP and is required for movement of the ribosome along the mRNA during translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> elongation factor Ts </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that regenerates elongation factor Tu in the elongation stage of protein synthesis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> elongation factor Tu </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein taking part in the elongation stage of protein synthesis; forms a complex with GTP and a charged amino acid and then delivers the charged tRNA to the ribosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> embryo </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of human development between zygote and fetus, typically the first eight weeks of human development. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> embryonic stem cell </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A totipotent cell from the inner layer of the blastocyst, can be cultured from a preimplantation embryo. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> emery's rule </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Social parasites and their hosts share common ancestry and hence are closely related to each other. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> empiric risk </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Probability that something will recur based on empirical evidence, rather than theory or guess; used to predict traits in a population based on past observations of that population. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> end labeling </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method for adding a radioactive or chemical label to the ends of DNA molecules. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> endangered species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A species that is likely to become extinct in all or a major portion of its range. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> endemic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Of a species, restricted to a specified region or locality. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> endocrine system </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A system of glands, organs and tissues, along with the hormones they secrete into the bloodstream, which together regulate animal physiology, reproduction, and behavior. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> endoderm </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The inner germ layer of an embryo; formed by gastrulation.Distinct from mesoderm and ectoderm. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> endonuclease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzyme that cleaves a nucleic acid. </div> </div> </div> <div class="wrap"> <strong> endoparasite </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Parasite that lives inside the body of its host. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> endoplasmic reticulum </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A labyrinth of membranous intracellular tubules on which proteins, lipids, and sugars are synthesized. </div> </div> </div> <div class="wrap"> <strong> endosymbiotic theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> States that some membrane-bounded organelles, such as mitochondria and chloroplasts, in eukaryotic cells originated as free-living eubacterial cells that entered into an endosymbiotic relation with a eukaryotic host cell and evolved into the present-day organelles; supported by a number of similarities in structure and sequence between organelle and eubacterial DNAs. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> endotherms </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that control body temperature internally. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> energetic war of attrition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A model that assumes that each individual does not have access to information on its opponent.s RHP. Instead, each individual keeps fighting until an individual threshold of costs, which could build up either as a result of performing non-injurious agonistic behaviors or receiving injuries, is reached. The weaker individual should reach its threshold first. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> energy equivalence rule </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Rule posing that the energy spent by a population is independent of the body mass of its individuals (a population of mice uses roughly the same energy as one of mice). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> energy flow </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In an ecological context, the flow of energy through trophic levels or major functional groups of organisms in an ecosystem; typically includes production, consumption, assimilation, non-assimilation losses (feces), and respiration (maintenance costs). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> engrailed </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A homeodomain containing protein that is expressed in the anterior region of 14 evenly spaced "stripes" during early Drosophila embryonic development. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/enhancer-163">enhancer</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A regulatory DNA sequence that, when bound by specific proteins called transcription factors, enhances the transcription of an associated gene. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> enhancer trap </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A system that allows investigators to find endogenous enhancers in a genome. The reporter gene in an enhancer trap is often based on a transposable element that can easily insert into the genome at random locations. This reporter gene has minimal promoter sequence so it is only expressed when it inserts near an endogeous sequence that results in gene transcription. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/environment-254">environment</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Usually, the complex of external physical, chemical, and biotic factors that may affect a population, an organism, or the expression of an organism's genes; more generally, anything external to the object of interest (e.g., a gene, an organism, a population) that may influence its function or activity. Thus, other genes within an organism may be part of a gene's environment, or other individuals in a population may be part of an organism's environment. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> environmental correlation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of the degree to which two traits respond to variation in the same environmental factors. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> environmental deviation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The difference between the phenotypic and genotypic values caused by the environment. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> environmental variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any phenotypic variance resulting from differing environmental pressures on portions of a population. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> enzymatic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a process mediated by an enzyme. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/enzyme-16">enzyme</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A macromolecule, usually a protein, that catalyzes biochemical reactions, lowering the activation energy and increasing the rate of reaction. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> epicormic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A shoot arising spontaneously from an adventitious or dormant bud on the stem or branch of a woody plant often following exposure to increased light levels or fire. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> epidemiology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of the frequency and determinants of disease across populations. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/epigenetic-process-epigenetic-epigenetics-98">epigenetic process</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A reversible process that affects the expression of genes; often occurring on top of ("epi") genetic material, and accumulating throughout an organisms's life. Example) the methylation of DNA. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> epigenomic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The pattern of epigenetic silencing across an entire genome of an organism. </div> </div> </div> <div class="wrap"> <strong> episome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Plasmid capable of integrating into a bacterial chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/epistasis-222">epistasis</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The interaction of nonallelic genes to control a phenotype in a different gene; contrast to same-gene allelic interactions to control a single-gene phenotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> epistatic gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Masks or suppresses the effect of a gene at a different locus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> epistatic selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The type of selection in which fitness depends upon nonadditive interactions between alleles at different loci. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> epistatic variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The portion of the phenotypic (and genotypic) variance that is due to epistasis, that is, interactions among gene loci. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> epitope </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Part of a protein that is recognized by an antibody. <div class="px10">Huub Schelleken</div> </div> </div> </div> <div class="wrap"> <strong> equational division </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The second meiotic division; any cell division that does not reduce chromosome number, and creates equal halves, having divided along the equatorial axis of the cell. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> equilibrium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An unchanging condition, as of population size or genetic composition. Also, the value (e.g., of population size, allele frequency) at which this condition occurs. An equilibrium need not be stable. See also stability, unstable equilibrium. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> equilibrium concept </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Especially with regard to models of ecosystems, the concept attaches fundamental significance to the idea that there is a steady state toward which populations return when disturbed or toward which communities evolve, even when disturbed. The conceptual framework focuses attention on average and long-term states, as opposed to transient dynamics and variation. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> equilibrium density gradient centrifugation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method used to separate molecules or organelles of different density by centrifugation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> erythroblast </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of red blood cell that has a nucleus. </div> </div> </div> <div class="wrap"> <strong> erythrocyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Red blood cell, shaped like a disc with a concave depression on both sides, carrier of hemoglobin. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> erythroid cell </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The progenitor cell of erythrocytes. </div> </div> </div> <div class="wrap"> <strong> essentialism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The philosophical view that all members of a class of objects (such as a species) share certain invariant, unchanging properties that distinguish them from other classes. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> estrogen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A steroid hormone produced by the ovaries. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> ethologists </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Scientists who study animal behavior. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/eubacteria-129">eubacteria</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the three primary divisions of life. Eubacteria consist of unicellular organisms with prokaryotic cells and include most of the common bacteria. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> eucalypts </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Woody plants belonging to three closely related genera: Eucalyptus, Corymbia and Angophora. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> euchromatin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromatin that undergoes condensation and decondensation in the course of the cell cycle. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/eugenics-157">eugenics</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The practice of controlled breeding in humans with the goal of achieving specific traits among offpsring; usually characterized by a social goal. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/eukaryote-eucariote-294">eukaryote</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Eukaryotes are organisms whose cells contain a nucleus and other organelles. There is a wide range eukaryotic organisms, including all animals, plants, fungi, protists and most algae, and eukaryotes may be either single-celled or multicellular <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> eukaryotic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describing a characteristic of a eukaryote. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Euler-Mascheroni constant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mathematical constant denoted by the greek letter gamma. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> euploid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A term describing a somatic cell containing the normal number of chromosomes for that species; typcially the number is a multiple of the hapoloid number. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> eusocial </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Groups that display each of the following three traits: cooperative care of young; non-reproducing worker castes; and an overlap of at least two generations of life stages capable of contributing to colony labor. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> eusocial </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Highly specialized sociality generally including individuals of one generation living together, cooperative care of young, division of individuals into nonreproductive or reproductive castes. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> eutherian </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A taxon that includes placental mammals (including humans). </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/evolution-78">evolution</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Evolution is a process that results in changes in the genetic material of a population over time </div> </div> </div> <div class="wrap"> <strong> evolutionarily significant units </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Populations of threatened or endangered organisms that need to be saved from extinction. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> evolutionarily stable strategy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A phenotype such that, if almost all individuals in a population have that phenotype, no alternative phenotype can invade the population or replace it. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> evolutionary allometry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The relationship of x and y that are traits measured in different species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> evolutionary arms race </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An evolutionary struggle between organisms with co-evolving traits that develop adaptations and counter-adaptations against each other, resembling an arms race. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> evolutionary constraint </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any biological factor that slows the rate of adaptive evolution. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> evolutionary fitness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The probability that the genetic contribution of an individual's specific trait or traits will not die out in future generations; calculated as the number of offspring contributed by an individual relative to the number of offspring produced by other members of the population. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> evolutionary grade </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of species that have evolved the same state in one or more characters; typically constitute a paraphyletic group. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> evolutionary reversal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The evolution of a character from a derived state back toward a condition that resembles an earlier state. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> evolutionary synthesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The reconciliation of Darwin's theory with the findings of modern genetics, which gave rise to a theory that emphasized the coaction of random mutation, selection, genetic drift, and gene flow; also called the modern synthesis. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> evolutionary trajectories </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pathways that populations traverse across adaptive landscapes during evolution, tracing the ways that the joint allele frequencies or mean phenotypes might evolve. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> ex vivo gene therapy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A clinical therapy that applies genetic alteration to cells removed from a patient, followed by re-implanation of the same cells. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> exaptation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The evolution of a function of a gene, tissue, or structure other than the one it was originally adapted for; can also refer to the adaptive use of a previously nonadaptive trait. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> excision repair </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A DNA repair mechanism, usually enzyme-catalyzed, that invovles the removal of damaged nucleotides, and replacement of the correct sequence, guided by the intact complementary DNA strand. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> exhabitational </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms who are relatively independent physically, but interact directly. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> exit site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of three sites in a ribosome occupied by a tRNA. In the elongation stage of translation, the tRNA moves from the peptidyl (P) site to the E site from which it then exits the ribosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/exon-exons-270">exon</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The coding sections of an RNA transcript, or the DNA encoding it, which are translated into a protein. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> exon shuffling </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The formation of new genes by assembly of exons from two or more preexisting genes. The classical model of exon shuffling generates new combinations of exons mediated via recombination of intervening introns; however, exon shuffling can also come about by retrotransposition of exons into preexisting genes. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> exonic splicing enhancer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequences located in exons adjacent to 5' and 3' splice sites that are required for proper recognition of the splice sites by the spliceosome. These enhancers are position dependent. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> exonuclease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzyme that cleaves one nucleotide at a time in the 3' --> 5' direction. </div> </div> </div> <div class="wrap"> <strong> expanding trinucleotide repeat </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mutation in which the number of copies of a trinucleotide (or some multiple of three nucleotides) increases in succeeding generations. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> expected heterozygosity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proportion of individuals that are expected to be heterozygous at a locus when the Hardy-Weinberg assumptions are met. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> expected outcome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The predicted outcome of observable events in an experiment. </div> </div> </div> <div class="wrap"> <strong> exponential population growth </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Unlimited growth of a population in an unlimited environment. Represented by a J-shaped curve when population size is plotted over time. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> expressed-sequence tag </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Unique fragment of DNA from the coding region of a gene, produced by the reverse transcription of cellular RNA. Parts of the fragments are sequenced so that they can be identified. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> expression vector </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cloning vector containing DNA sequences such as a promoter, a ribosome-binding site, and transcription initiation and termination sites that allow DNA fragments inserted into the vector to be transcribed and translated. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/expressivity-158">expressivity</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Degree to which a trait is expressed. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> extent </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The range over which a physical or temporal event occurs. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> extinction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Occurs when the death of last individual of a species perishes; it is the end of the organism and the taxa in which it belongs. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> extremophiles </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that live in an environment where conditions are so extreme that few other species can survive there. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> extrinsic hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Prediction of the number of observed individuals with specific characteristics based on calculations performed before the experiment is completed. </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="F"><div class="padleft10px fleft bold px15">F</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> F factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Episome of E. coli that controls conjugation and gene exchange between E. coli cells. The F factor contains an origin of replication and genes that enable the bacterium to undergo conjugation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> F1 cross </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cross between two pure-breeding or homozygous lines. Such homozygous lines are also called parental lines. Parental lines differ in a pair of contrasting traits (e.g, red eyes or white eyes in Drosophila, or tall or short pea plants). Females from one of the parental lines (Parental Line 1 or P1) are mated to males from the other parental line (Parental Line 2 or P2). The mating is called the F1 cross, and the progeny resulting from this mating are the F1 progeny or F1 generation. <div class="px10">Terry McGuire</div> </div> </div> </div> <div class="wrap"> <strong> F1 generation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Offspring of the initial parents (P) in a genetic cross. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> F1 reciprocal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The reverse of an F1 cross. If females from one line (Parental Line 1) are crossed with males from Parental Line 2 for an F1 cross, the reciprocal cross would use males from Parental Line 1 and females from Parental Line 2. P2 females can be mated with P1 males. Progeny from this mating are the reciprocal F1 progeny or the reciprocal F1 generation. </div> </div> </div> <div class="wrap"> <strong> F2 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The F2 cross is the quintessential segregating generation. For a single autosomal gene, the F2 generation is the first generation in which both parental phenotypes occur. For two or more genes, it is the first generation in which all new combinations of phenotypes can occur at the same time. These new phenotypes reflect independent assortment among the allele genes that formed the gametes of the F1 generation. <div class="px10">Terry McGuire</div> </div> </div> </div> <div class="wrap"> <strong> F2 generation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Offspring of the F1 generation in a genetic cross; the third generation of a genetic cross. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> facilitation succession model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Where species modify the environment in a way that allows other species to colonize. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> facultative </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Optional, discretionary. The opposite of obligate. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> facultative slave-makers </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of social parasitism in ants where colonies can survive with or without slave ants. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> familial Down syndrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Caused by a Robertsonian translocation in which the long arm of chromosome 21 is translocated to another chromosome; tends to run in families. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/family-history-178">family history</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A diagram representing the genealogical history of an individual. In medicine, a family history also includes any health information known about an individual's relatives. </div> </div> </div> <div class="wrap"> <strong> fecundity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The quantity of gametes (usually eggs) produced by an individual. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> feral </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organism that has escaped domestication and returned to a wild state. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> fertilization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fusion of gametes, or sex cells, to form a zygote. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> fetal cell sorting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Separation of fetal cells from maternal blood. Genetic testing on the fetal cells can provide information about genetic diseases and disorders in the fetus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> fetus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A term for the prenatal mammal; a prenatal human after the eighth week of development. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> fire regime </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The characteristic pattern of fire in a particular place. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> first filial cross </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Crossing of two parental lines. </div> </div> </div> <div class="wrap"> <strong> first polar body </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the products of meiosis I in oogenesis; contains half the chromosomes but little of the cytoplasm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/fitness-83">fitness</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The success of an entity in reproducing; hence, the average contribution of an allele or genotype to the next generation or to succeeding generations. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> fitness cost </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A reduction in fitness of a trait occurring in correlation with a benefit or increase in fitness of another trait. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> fitness function </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The curve that describes the relationship between fitness and a phenotypic trait. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> fitness surface </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A three-dimensional representation of the relationship between two phenotypic traits and individual fitness. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> fixation index </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Wright's measure of population differentiation. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> fixed </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A population in which all members are homozygous for the same allele at a given locus (antonyms: segregating, polymorphic). <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> flanking direct repeat </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Short, directly repeated sequence produced on either side of a transposable element when the element inserts into DNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> fluorescence assay </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method that tags a biological sample with a fluorophore in order to monitor that sample. </div> </div> </div> <div class="wrap"> <strong> fluorescence in situ hybridization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A technique that binds fluorescently labeled DNA or RNA probes to complementary sequences occuring in cells and tissues; used to label the location of specific sequences in a biological sample.Abbreviated as FISH. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> food web </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Feeding relationships or organisms within an ecosystem or community. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> footprinting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A technique in biology that attempts to map protein binding sites on DNA by examining the areas on a DNA molecule that are protected from nuclease activity due to protein binding. </div> </div> </div> <div class="wrap"> <strong> foraging behavor: </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Predicts that foraging options that deliver the highest payoff should be favored by foraging animals because it will have the highest fitness payoff. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> forbs </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Broad-leaved herbaceous plants. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> formicine ants </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Ants of the subfamily Formicinae. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> forward mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Alters a wild-type phenotype. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> foundation species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species that exert influence on a community not through their trophic interactions, but by causing physical changes in the environment. These organisms alter the environment through their behavior or their large collective biomass. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> founder effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The principle that the founders of a new population carry only a fraction of the total genetic variation in the source population. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> founder event </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of bottleneck, defined as the creation of a new population by a small number of colonists. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> fragile site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Constriction or gap that appears at a particular location on a chromosome when cells are cultured under special conditions. One fragile site on the human X chromosome is associated with mental retardation (fragile-X syndrome) and results from an expanding trinucleotide repeat. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/frameshift-mutation-frame-shift-mutation-frameshift-203">frameshift mutation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> fraternal twins </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Nonidentical twins that arise when two different eggs are fertilized by two different sperm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> free radical </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A highly reactive molecule that has at least one unpaired, or free, electron. </div> </div> </div> <div class="wrap"> <strong> frequency </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Usually used to mean proportion (e.g., the frequency of an allele is the proportion of gene copies having that allelic state). <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> frequency dependent selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of natural selection in which the fitness of each genotype or phenotype depends on its frequency in the population. In positive frequency dependence, fitness increases as the genotype or phenotype becomes more common, and in negative frequency dependence, fitness increases as the genotype or phenotype becomes rarer. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> frequency distribution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Graphical way of representing values. In genetics, usually the phenotypes found in a group of individuals are displayed as a frequency distribution. Typically, the phenotypes are plotted on the horizontal (x) axis and the numbers (or proportions) of individuals with each phenotype are plotted on the vertical (y) axis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> function </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The way in which a character contributes to the fitness of an organism. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> functional dna </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Segments of DNA that code for proteins and essential RNA molecules, as well as sequences that help turn genes on and off. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> functional genomics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Area of genomics that studies the functions of genetic information contained within genomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> fusain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fossilized charcoal. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> fusion pattern </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method of using protein fusion to infer gene function. If two proteins that are separate in one species exist as a fused protein in another species, the two separate proteins in the first species may be functionally related. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> fusion protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein formed from transcription of two or more genes in sequence, with no stop codon in between them. They can occur naturally in cancer cells, and create complex proteins involved in cancerous mechanisms. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="G"><div class="padleft10px fleft bold px15">G</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> G-banding </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A staining protocol for chromosomes. Chromosomes are generally pretreated with an enzyme that facilitates staining with Giemsa dye. Each chromosome has a unique staining pattern that allows it to be distinguished from other chromosomes. </div> </div> </div> <div class="wrap"> <strong> G-matrix </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A square matrix with additive genetic variances for the traits on the diagonal and additive genetic covariances on the off-diagonal. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> G0 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Nondividing stage of the cell cycle. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> G1 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage in interphase of the cell cycle in which the cell grows and develops. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> G1/S checkpoint </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Important point in the cell cycle. After the G1/S checkpoint has been passed, DNA replicates and the cell is committed to dividing. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> G2 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of interphase in the cell cycle that follows DNA replication. In G2, the cell prepares for division. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> G2/M checkpoint </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Important point in the cell cycle near the end of G2. After this checkpoint has been passed, the cell undergoes mitosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gain-of-function mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Produces a new trait or causes a trait to appear in inappropriate tissues or at inappropriate times in development. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> game theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A branch of economic theory devoted to modeling interactions between competing individuals or organizations. In biology, "evolutionary game theory" is used to model "competition" in evolutionary time between alternative behavioral strategies. The aim is to determine which strategy, out of a set of alternatives, would be favored by natural selection. Evolutionary game theory has been applied to a wide range of problems in animal behavior but fighting behavior was the first application. The Hawk-Dove game is an example of a model based on evolutionary game theory. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gamete-gametes-311">gamete</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The reproductive cell of an organism; typically contains half or a reduced number of chromosomes compared to a somatic cell. In mammals, gametes are haploid cells that fuse to form a diploid zygote. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gamete intrafallopian transfer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method of transferring sperm and ooocytes to a woman's uterine tube, to assist in human reproduction. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gametes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The plural form of gamete. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gametic array </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method of describing in mathematical terms that the sum of the proportion of gametes that carries a specific allele is equal to 1. For example, a heterozygote embryo of genotype Aa has the gametic array of 1/2A + 1/2a = 1. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> gametic phase disequilibrium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A nonrandom relationship between the alleles present at two or more loci, which can cause a genetic correlation. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> gametophyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Haploid phase of the life cycle in plants. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gamma diversity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Combines alpha diversity and beta diversity. Also called large-scale landscape diversity. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gap-genes-211">gap genes</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In fruit flies, set of segmentation genes that define large sections of the embryo. Mutations in these genes usually eliminate whole groups of adjacent segments. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gastrula </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The term for a three-layered embryo that forms after the gastrulation event. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gatekeeper </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Tumor suppressor genes or proteins that regulate cellular responses that prevent the survival or proliferation of potential cancer cells. <div class="px10">Judith Campisi</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gel-electrophoresis-286">gel electrophoresis</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Gel electrophoresis is a laboratory method used to separate mixtures of DNA, RNA, or proteins according to their sizes </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gene-29">gene</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A region of DNA (deoxyribonucleic acid) coding either for the messenger RNA encoding the amino acid sequence in a polypeptide chain or for a functional RNA molecule. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> gene action </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The manner in which genotype affects phenotype, including additivity, dominance, pleiotropy, and epistasis. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> gene array </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A technology that allows investigators to measure the relative abundance of transcripts of specific genes by binding labeled cDNA probes from cells to a microchip with covalently attached microscopic spots of DNA, with each spot representing a single gene. </div> </div> </div> <div class="wrap"> <strong> gene cloning </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Inserting DNA fragments into bacteria in such a way that the fragments will be stable and copied by the bacteria. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gene complex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of two or more genes that are members of the same family and in most cases are located in close proximity to one another in the genome, often in tandem separated by various amounts of intergenic, noncoding DNA. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> gene conversion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process involving the unidirectional transfer of DNA information from one gene to another. In a typical conversion event, a gene or part of a gene acquires the same sequence as the other allele at that locus (intralocus or intraallelic conversion), or the same sequences as a different, usually paralogous, locus (interlocus conversion). One consequence of gene conversion may be the homogenization of sequences among members of a gene family. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gene-doping-109">gene doping</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Modifying the genetic makeup of an individual with the specific purpose of improving athletic performance. </div> </div> </div> <div class="wrap"> <strong> gene duplication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When new genes arise as copies of preexisting gene sequences. The result can be a gene family. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gene-expression-49">gene expression</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process by which the genetic information in DNA is transcribed into mRNA. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gene expression profiling </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method for defining the particular set of gene expression patterns in a particular source of tissue or cells; the use of DNA microarrays to detect mRNA expression sets with reverse transcription to labeled cDNAs. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gene family </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Two or more loci with similar nucleotide sequences that have been derived from a common ancestral sequence. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gene-flow-227">gene flow</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The movement of alleles between previously separate populations caused by migration and subsequent mating. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gene frequency </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> See allele frequency. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gene-interaction-243">gene interaction</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Interactions between genes at different loci that affect the same characteristic. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gene-knockdown-12">gene knockdown</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Temporary decrease in gene expression caused by an experimental technique, often an antisense oligo. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gene-knockout-74">gene knockout</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Permanent change in DNA leading to the loss of function of a gene, caused by a manipulation of the organism's DNA in a laboratory followed by breeding to produce a population of organisms that are homozygotes for the changed gene. <div class="px10">Jon Moulton</div> </div> </div> </div> <div class="wrap"> <strong> gene mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Affects a single gene or locus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gene neighbor analysis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Analysis of the locations of genes in different species to infer gene function. If two genes are consistently linked in different species, they may be functionally related. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gene ontology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A hierarchical organization of concepts (ontology) with three organizing principles: molecular function, the tasks done by individual gene products, an example of which is 'transcription factor'; biological process, broad biological goals, such as mitosis, that are accomplished by ordered assemblies of molecular functions; cellular component, subcellular structures, locations and macromolecular complexes (examples include the nucleus and the telomere). <div class="px10">Yandell, M. D. and Majoros, W. H. Genomics and natural language processing. Nature Reviews Genetics 3, 601-610 (2002)</div> </div> </div> </div> <div class="wrap"> <strong> gene pool </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The totality of the genes of a given sexual population. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> gene regulation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mechanisms and processes that control the phenotypic expression of genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gene regulatory site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A section of DNA where regulatory proteins such as transcription factors bind preferentially; binding of regulatory proteins to such as site changes gene expression. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gene sequencing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Determining the complete sequence of a molecule or molecules of DNA, often through highly automated procedures. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> gene silencer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene sequence that represses transcription, yet has similar properties to a gene enhancer. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gene targeting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A technique that modifies genes using homologous recombination, and uses a specific vector to do it; may involve the removal of exons or imposition of point mutations. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/gene-therapy-65">gene therapy</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Use of recombinant DNA to treat a disease or disorder by altering the genetic makeup of the patient's cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gene-environment interaction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In epidemiological studies, the differential effect that environmental conditions can have on an organism depending on the organism's genotype; in studies of disease, the observed effect of behavior and environmental exposures on human health, through the corrleated tracking of specific genotypes and vulnerabilities to disease. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> general transcription factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transcription factors are proteins that are involved in the process of converting, or transcribing, DNA into RNA <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> generalist preadators </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Predators that consume alternate prey. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> generalized transduction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transduction in which any gene may be transferred from one bacterial cell to another by a virus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> generic drug </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A copy of a drug that is introduced after the patent expires. <div class="px10">Huub Schelleken</div> </div> </div> </div> <div class="wrap"> <strong> genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A sequence of nucleotides that code for a trait; the basic unit of inheritance. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> genetic bottleneck </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sampling error that arises when a population undergoes a drastic reduction in population size; leads to genetic drift. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> genetic clone </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genetically identical copy of an individual, cell or fragment of DNA. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-code-13">genetic code</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The genetic code is a set of rules that defines how the four-letter code of DNA is translated into the 20-letter code of amino acids, which are the building blocks of proteins. </div> </div> </div> <div class="wrap"> <strong> genetic conflict </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Antagonistic fitness relationships between alleles at different loci in a genome. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> genetic correlation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phenotypic correlation due to the same genes affecting two or more characteristics. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-counseling-54">genetic counseling</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Educational process that attempts to help patients and family members deal with all aspects of a genetic condition. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-cross-181">genetic cross</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A controlled mating. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> genetic differentiation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Differences between populations in allele frequencies at one or more loci, or in mean phenotypes in a common environment. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> genetic distance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any of several measures of the degree of genetic difference between populations, based on differences in allele frequencies. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-drift-201">genetic drift</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The change in frequency of alleles in a population over time, due to changes in the transmission of gametes to successive generations among individuals in a finite population. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-engineering-102">genetic engineering</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Common term for recombinant DNA technology. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> genetic identity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure indicating the proportion of genes that are identical between two populations; on a small scale, when two (or more) genetic sequences are exactly the same. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-information-nondiscrimination-act-gina-214">Genetic Information Nondiscrimination Act</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A federal law will protect Americans against discrimination based on their genetic information when it comes to health insurance and employment. <div class="px10">http://www.genome.gov</div> </div> </div> </div> <div class="wrap"> <strong> genetic load </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any reduction of the mean fitness of a population resulting from the existence of genotypes with a fitness lower than that of the most fit genotype. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> genetic map </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A linear representation of the arrangement of genes on a chromosome, typically based on the frequency of recombination between different loci. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> genetic marker </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any gene or DNA sequence used to identify a location on a genetic or physical map. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> genetic maternal effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Determines the phenotype of an offspring. With genetic maternal effect, an offspring inherits genes for the characteristics from both parents, but the offspring's phenotype is determined not by its own genotype but by the nuclear genotype of its mother. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-screen-200">genetic screen</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An experiment in which mutant organisms are generated in the laboratory and isolated based on a specific, desired phenotype. </div> </div> </div> <div class="wrap"> <strong> genetic screening </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Analyzing DNA to determine the presence of a genetic variation that is responsible for an inherited disease. </div> </div> </div> <div class="wrap"> <strong> genetic substitution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The complete replacement of one allele by another within a population or species over evolutionary time. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-test-genetic-test-104">genetic test</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In humans, a medical test using blood or tissue that can determine if there is a specific known sequence in the patient's genome. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> genetic variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Component of the phenotypic variance that is due to genetic differences among individual members of a population. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genetic-variation-68">genetic variation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Naturally occurring genetic differences among organisms in the same species. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> genetic-environmental interaction variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Component of the phenotypic variance that results from an interaction between genotype and environment. Genotypes are expressed differently in different environments. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> genetically engineered organism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any organism whose genetic makeup has been artificially modified, either by intentional directed breeding or transgenic insertion. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> genetically modified foods </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Foods derived from genetically modified crops. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> genic balance system </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sex-determining system in which sexual phenotype is controlled by a balance between genes on the X chromosome and genes on the autosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> genic interaction variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Component of the genetic variance that can be attributed to genic interaction (interaction between genes at different loci). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> genic selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of selection in which the single gene is the unit of selection, such that the outcome is determined by fitness values assigned to different alleles. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> genic sex determination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sex determination in which the sexual phenotype is specified by genes at one or more loci, but there are no obvious differences in the chromosomes of males and females. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genome-43">genome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genome is the complete set of genetic information in an organism. It provides all of the information required by an organism to function. </div> </div> </div> <div class="wrap"> <strong> genome sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The order of nucleotides of a particular genome. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> genome size </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The total number of DNA base pairs contained within one copy of a genome. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genome-wide-association-study-gwas-genome-wide-187">genome wide association study</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A case-control study in which genetic variation, often measured as SNPs that form haplotypes across the entire genome, is compared between people with a particular condition and unaffected individuals. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genomic-imprinting-266">genomic imprinting</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Differential expression of a gene that depends on the sex of the parent that transmitted the gene. If the gene is inherited from the father, its expression is different than if it is inherited from the mother. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> genomic library </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Collection of bacterial or phage colonies containing DNA fragments that consist of the entire genome of an organism. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genomics-126">genomics</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genomics is the large-scale study of all the genes in an organism. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/genotype-234">genotype</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genotype is the particular the combination of alleles for a particular gene or locus. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> genotypic array </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A prediction of the possible genotypic combinations in an offspring based on the genotypes of two parents. </div> </div> </div> <div class="wrap"> <strong> genotypic frequencies </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The proportion of each of the various genotypes present in a population or sample of a population. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> genotypic frequency </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proportion of a particular genotype. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> genotypic value </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The phenotype produced by a given genotype averaged across environments. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> genotypic variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The magnitude of the phenotypic variance that is due to all genetic causes, corresponding to the sum of the additive, dominance, and epistatic variances. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> geographic variation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Differences among spatially distributed populations of a species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> geomorphology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of landforms and the geological processes that shape them. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> germ-line mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mutation in a germ-line cell (one that gives rise to gametes). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> germ-plasm theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> States that cells in the reproductive organs carry a complete set of genetic information. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> global climate change </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A change in the statistical distribution of weather over periods of time that can range from decades to millions of years. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> globin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The protein that carries the oxygen in red blood cells. </div> </div> </div> <div class="wrap"> <strong> glycolipid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A complex molecule made of a carbohydrate sugar bonded to a lipid, usually embedded in cell membranes. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> glycoprotein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein with carbohydrate modifications; can be secreted from the cell or embedded in the membrane; interactions between glycoproteins on adjacent cells permit cell-cell communication. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/goodness-of-fit-120">goodness of fit</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An expression in statistics referring to the measure of how closely aligned a function derived from actual cumulative data is to a predicted model function. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> gradualism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The proposition that large differences in phenotypic characters have evolved through many slightly different intermediate states. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> green fluorescent protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein originally isolated from the jellyfish (Aequorea victoria) that retains the property of fluorescing green when exposed to blue light and when fused to other cellular proteins. </div> </div> </div> <div class="wrap"> <strong> group I intron </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Belongs to a class of introns in some ribosomal RNA genes that are capable of self-splicing. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> group II intron </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Belongs to a class of introns in some protein-encoding genes that are capable of self-splicing and are found in mitochondria, chloroplasts, and a few eubacteria. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> group predation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Carnivorous interactions involving many small individuals consuming a larger one. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> group selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The differential rate of origination or extinction of whole populations (or species, if the term is used broadly) on the basis of differences among them in one or more characteristics. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> guanine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Purine in DNA and RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> guide RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA molecule that serves as a template for an alteration made in mRNA during RNA editing. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> gynandromorph </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Individual organism that is a mosaic for the sex chromosomes, possessing tissues with different sex-chromosome constitutions. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="H"><div class="padleft10px fleft bold px15">H</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> habitat </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The physical environment (i.e., the chemical resources and physical conditions) of an organism or organisms. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> habitat enhancement </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process of increasing the suitability of a site as habitat for some desired species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> habitat fragmentation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process of breaking a natural landscape into fewer, smaller and more disjointed areas of habitat. Loss of total area and variety of habitats is called change in composition. Change in the variety, spatial arrangement, shape and size of habitats is change in configuration. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> habitat patchiness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Landscape spatial heterogeneity caused by spatial and temporal variation in the distribution and abundance of vital resources, as well as in geological and ecological processes. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> habitat selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The capacity of an organism (usually an animal) to choose a habitat in which to perform its activities. Habitat selection is not a form of natural selection. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> hairpin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Secondary structure formed when sequences of nucleotides on the same strand are complementary and pair with each other. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/hairpin-loop-mrna-314">hairpin loop (mRNA)</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A hairpin loop is an unpaired loop of messenger RNA (mRNA) that is created when an mRNA strand folds and forms base pairs with another section of itself. Hairpins are a common type of secondary structure in RNA molecules </div> </div> </div> <div class="wrap"> <strong> Hamilton's rule </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A formula posited by William Donald Hamilton that specifies the conditions for reproductive altruism to evolve; attempts to explain;behavior whereby benefit is given to a relative at the expense of an individual's own reproductive success. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> haplodiploid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A sex determination system in which sex is determined by the number of copies of the genome in the cells of the individual, rather than the presence or absence of a sex chromosome. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/haploid-309">haploid</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes cells that contain a single set of chromosomes. <div class="px10">© Nature Education </div> </div> </div> </div> <div class="wrap"> <strong> haploid state </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The condition or stage of a reproductive cycle or process whee a cell contains only one set of chromosomes. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> haploinsufficiency </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The appearance of a mutant phenotype in an individual cell or organism that is heterozygous for a normally recessive trait. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> haploinsufficient gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Must be present in two copies for normal function. If one copy of the gene is missing, a mutant phenotype is produced. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/haplotype-haplotypes-142">haplotype</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A haplotype is a group of genes, which is inherited together by an organism from a single parent </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/hapmap-project-19">HapMap Project</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An international consortium of scientists working together to catalog the genetic variation in the human genome. </div> </div> </div> <div class="wrap"> <strong> Hardy-Weinberg assumption </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Allele frequencies will remain constant over time if there are no forces to change them. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/hardy-weinberg-equation-299">Hardy-Weinberg equation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The Hardy-Weinberg equation is a mathematical expression that can be used to calculate the genetic variation of a population at equilibrium. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/hardy-weinberg-equilibrium-122">Hardy-Weinberg equilibrium</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The Hardy-Weinberg equilibrium is a principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Hardy-Weinberg law </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Important principle of population genetics stating that, in a large, randomly mating population not affected by mutation, migration, or natural selection, allelic frequencies will not change and genotypic frequencies stabilize after one generation in the proportions p2 (the frequency of AA), 2pq (the frequency of Aa), and q2 (the frequency of aa), where p equals the frequency of allele A and q equals the frequency of allele a. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> harem </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An aggregation of females that can be monopolized by a single male for the purpose of mating. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> hawk-dove game </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> This particular model pits a Hawk strategy (i.e., always try to injure your opponent and only withdraw from the contest if an injury is received) against a Dove strategy (i.e., always use a non-injurious display if the rival is another Dove and always withdraw if the rival is a Hawk). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> heat capacity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The heat required to raise the temperature of a substance one degree Celsius. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Heat shock element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A DNA sequence to which heat shock transcription factors bind when activated. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> Heat shock transcription factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A transcription factor that becomes activated upon cellular stress, resulting in its trimerization, binding to heat shock elements, and induction of transcription of a number of proteins. </div> </div> </div> <div class="wrap"> <strong> heat-shock protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Produced by many cells in response to extreme heat and other stresses; helps cells prevent damage from such stressing agents. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> HeLa cell </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An immortalized human cell line frequently used in biological research. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/helicase-307">helicase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Helicase is an enzyme that unwinds and separates the two strands of the DNA double helix </div> </div> </div> <div class="wrap"> <strong> helix-loop-helix </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An area of a protein that folds in a predictable way and characterizes a group of transcription factors. Specifically, helix-loop-helix is a polypeptide that has a structure of two alpha-helices connected by a loop. </div> </div> </div> <div class="wrap"> <strong> helix-turn-helix </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A common protein motif characterized by two adjacent alpha helices that make contact with DNA and regulate gene transcription. </div> </div> </div> <div class="wrap"> <strong> hemagglutinin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type I integral membrane glycoprotein that binds to cell-surface receptors and facilitates fusion between the viral envelope and endosomal membrane. It is the main target antigen of the humoral immune response to influenza viruses. <div class="px10">Kanta Subbarao & Tomy Joseph</div> </div> </div> </div> <div class="wrap"> <strong> hemicryptophytes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Plants with their perennating buds at or near the soil surface (e.g. many grasses). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> hemizygote </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organism that has only one allele at a given locus. </div> </div> </div> <div class="wrap"> <strong> hemizygous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Possessing a single allele at a locus. Males of organisms with XX-XY sex determination are hemizygous for X-linked loci, because their cells possess a single X chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> herbivore </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Animal adapted to eat plants. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/heritability-89">heritability</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The proportion of the variance in a trait in a population that is attributable to genetic variation (differences in genotype). Mathematically, the ratio of additive genetic variance to phenotypic variance. <div class="px10">© Nature Education </div> </div> </div> </div> <div class="wrap"> <strong> hermaphroditism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Condition in which an individual organism possesses both male and female reproductive structures. True hermaphrodites produce both male and female gametes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> heterochromatin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromatin that remains in a highly condensed state throughout the cell cycle, found at the centromeres and telomeres of most chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> heterochrony </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An evolutionary change in phenotype caused by an alteration of timing of developmental events. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> heteroduplex DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA consisting of two strands, each of which is from a different chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> heterogametic sex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The sex (male or female) that produces two types of gametes with respect to sex chromosomes. For example, in the XX-XY sex-determining system, the male produces both X-bearing and Y-bearing gametes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> heterokaryon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cell possessing two nuclei derived from different cells through cell fusion. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> heterokaryotype </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genome or individual that is heterozygous for a chromosomal rearrangement such as an inversion. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> heteromorphic chromosomes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A pair of chromosomes that share some genetic homology but differ in physical characteristics like size, shape, or staining patterns. </div> </div> </div> <div class="wrap"> <strong> heteroplasmy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Presence of two or more distinct variants of DNA within the cytoplasm of a single cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> heterosis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phenomenon in which the F1 generation has higher fitness than the parental strains or subpopulations that were crossed (mated) to produce them. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> heterotroph </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organism that cannot synthesize its own food and must consume other food sources to receive complete nutrition requirements. </div> </div> </div> <div class="wrap"> <strong> heterotrophs </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that obtain their food by eating other organisms or substances derived from them; organisms that cannot synthesize its own organic material and must obtain energy from other organisms. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> heterozygosity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In a population, the proportion of loci at which a randomly chosen individual is heterozygous, on average. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> heterozygote </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organism with a genotype that includes different alleles at a gene locus. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> heterozygote advantage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The phenomenon of the heterozygous genotype having a higher fitness (or other phenotypic value) than any homozygous genotype at the same gene locus. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> heterozygote screening </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Testing members of a population to identify heterozygous carriers of a disease-causing allele who are healthy but have the potential to produce children with the disease. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> heterozygotes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Individuals who have two different alleles at a locus (e.g., at a locus with two alleles, A and a, the heterozygote has genotype Aa). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> heterozygous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to an individual organism that possesses two different alleles at a locus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> heterozygous genotype </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genotype that has more than one type of allele at a gene locus. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> high-mobility group </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small, highly-charged proteins that vary in amount and composition in different tissues and different stages of the cell cycle; may play an important role in chromatin structure. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> highly repetitive DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA that consists of short sequences that are present in hundreds of thousands to millions of copies; clustered in certain regions of chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> HIPAA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A U.S. federal law that requires improved efficiency in health care delivery by standardized electronic data interchange and protection of confidentiality and security of health data. <div class="px10">http://www.hipaadvisory.com/REGS/HIPAAprimer.htm</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/histone-histones-278">histone</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein that is part of the histone family of basic proteins which associate with DNA in the nucleus and help to condense the DNA into a smaller volume. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> histone acetyl transferase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A family of proteins that is responsible for catalyzing the bonding of an acetyl group to specific lysines on histones, generally resulting in increased transcription at that locus. </div> </div> </div> <div class="wrap"> <strong> histone code </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The combination of all the different modifications that can occur on histones. </div> </div> </div> <div class="wrap"> <strong> histone deacetylase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein that catalyzes the removal of an acetyl group from histones. </div> </div> </div> <div class="wrap"> <strong> histone demethylase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein that catalyzes the removal of a methyl group from histones. </div> </div> </div> <div class="wrap"> <strong> histone methyltransferase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proteins that catalyze the addition of methyl groups to lysines or arginines in histone proteins, causing the DNA to be less available for transcriptional machinery. </div> </div> </div> <div class="wrap"> <strong> hitchhiking </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Change in the frequency of an allele due to linkage with a selected allele at another locus. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> HMG nuclear protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein component of chromatin that was named based on its mobility in polyacrilimide gels. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> holandric </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a trait that is encoded by a gene on the Y chromosome. </div> </div> </div> <div class="wrap"> <strong> Holliday intermediate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Structure that forms in homologous recombination; consists of two duplex molecules connected by a cross bridge. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Holliday junction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Model of homologous recombination that is initiated by single-strand breaks in a DNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> holoblastic cleavage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a cell division event during development that results in complete cleavage between the two daughter cells. Often this type of cleavage is evident in animals in which the zygotic stage does not have a large amount of yolk. </div> </div> </div> <div class="wrap"> <strong> holoenzyme </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Complex of enzyme and other protein factors necessary for complete function. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homeobox </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Conserved subset of nucleotides in homeotic genes. In Drosophila, it consists of 180 nucleotides that encode 60 amino acids of a DNA-binding domain related to the helix-turn-helix motif. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homeobox genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A large family of eukaryotic genes that contains a DNA sequence known as the homeobox. The homeobox sequence encodes a protein homeodomain about 60 amino acids in length that binds DNA. Most homeobox genes are transcriptional regulators. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> homeodomain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The region of a homeobox protein that can bind DNA. </div> </div> </div> <div class="wrap"> <strong> homeostasis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ongoing maintenance of equilibrium state in a cell or organism; maintained by biochemical processes that balance each other. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> homeotic complex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Major cluster of homeotic genes in fruit flies; consists of the Antennapedia complex, which affects development of the adult fly's head and anterior segments, and the bithorax complex, which affects the adult fly's posterior thoracic and abdominal segments. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homeotic genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genes that determine the developmental fate of entire segments of an animal. <div class="px10"> © 2008 by Sinauer Associates, Inc. All rights reserved. Sadava, D. Life: the science of biology. 8th Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homeotic mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutation that causes a transformation of one structure into another of the organism's structures. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> homogametic sex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The sex (male or female) that produces gametes that are all alike with regard to sex chromosomes. For example, in the XX-XY sex-determining system, the female produces only X-bearing gametes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homokaryotype </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genome or individual that is homozygous for a chromosomal rearrangement such as an inversion. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> homologous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Similar in position, structure, function, or characteristics. </div> </div> </div> <div class="wrap"> <strong> homologous dna </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Portions of DNA from different organisms that have similar sequences because they are derived from a common evolutionary ancestor. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> homologous genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Evolutionarily related genes, having descended from a gene in a common ancestor. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homologous pair of chromosomes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Two chromosomes that are alike in structure and size and that carry genetic information for the same set of hereditary characteristics. One chromosome of a homologous pair is inherited from the male parent and the other is inherited from the female parent. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homologous recombination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Exchange of genetic information between homologous DNA molecules. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homologous recombination repair </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A relatively error-free pathway that repairs DNA double-strand breaks using an undamaged sister chromatid or homologous chromosome as a template. <div class="px10">Judith Campisi</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/homology-198">homology</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Possession by two or more species of a character state derived, with or without modification, from their common ancestor. Homologous chromosomes are those members of a chromosome complement that bear the same genes. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> homomorphic chromosomes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Homologous chromosomes that are morphologically identical. </div> </div> </div> <div class="wrap"> <strong> homonymous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pertaining to biological structures that occur repeatedly within one segment of the organism, such as teeth or bristles. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> homoplasmy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Presence of only one version of DNA within the cytoplasm of a single cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> homoplasy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Possession by two or more species of a similar or identical character state that has not been derived by both species from their common ancestor; embraces convergence, parallel evolution, and evolutionary reversal. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> homozygosity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The frequency of homozygous genotypes, often symbolized as P or Q. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> homozygote </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An individual that has copies of the same allele at paired genetic loci. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> homozygotic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes twins that derive from the same zygote. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> homozygous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A diploid genotype or individual with two indistinguishable alleles at a given locus. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> homozygous line </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Another name for a "pure-breeding" line; a strain of organisms that are homozygous for the alleles associated with a particular phenotype. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> horizontal gene exchange </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transfer of genes from one organism to another by a mechanism other than reproduction. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> horizontal gene transfer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transfer of genetic information from one species to another in ways other than common descent. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> horizontal transfer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Movement of genes between species. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> horizontal transmission </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Movement of genes or symbionts (such as parasites) between individual organisms other than by transmission from parents to their offspring (which is vertical transmission). Horizontal transmission of genes is also called lateral gene transfer. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> Hox genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genes that control gross development in most plant and animal organisms along the major anterior-posterior axis; also called homeotic genes. <div class="px10">© Nature Education </div> </div> </div> </div> <div class="wrap"> <strong> Hpa II endonuclease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A methyltransferase that recognizes the sequence CCGG and is responsible for methylating the second cysteine. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/human-genome-project-hgp-112">Human Genome Project</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The Human Genome Project was an international research project that sequenced all of the genes in humans </div> </div> </div> <div class="wrap"> <strong> humoral immunity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of immunity resulting from antibodies produced by B cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/hybrid-239">hybrid</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An individual formed by mating between unlike forms, usually genetically differentiated populations or species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> hybrid dysgenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sudden appearance of numerous mutations, chromosome aberrations, and sterility in the offspring of a cross between a male fly that possesses P elements and a female fly that lacks them. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> hybrid vigor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phenomenon in which the F1 generation has higher fitness than the parental strains or subpopulations that were crossed (mated) to produce them. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> hybrid zone </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A region in which genetically distinct populations come into contact and produce at least some offspring of mixed ancestry. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> hybridization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pairing of two partly or fully complementary single-stranded nucleotide chains. The nucleotide chains may come from the same species or different species. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> hydrogen bond </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A weak electrostatic bond which arises from the attraction between the slight positive charge on a hydrogen atom and a slight negative charge on a nearby oxygen or nitrogen atom. <div class="px10"> © 2008 by Sinauer Associates, Inc. All rights reserved. Sadava, D. Life: the science of biology. 8th Edition.</div> </div> </div> </div> <div class="wrap"> <strong> hyperaccumulators </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Plants containing extremely large amounts of certain chemical elements (frequently metals or metallic compounds). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> hyperallometry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> For ontogenetic allometry, when the organ has a higher growth rate than the body as whole, a > 1; for static/evolutionary allometry, when an organ is proportionally larger in larger individuals/species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> hypermorphosis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An evolutionary increase in the duration of ontogenetic development, resulting in features that are exaggerated compared to those of the ancestor. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> hypostatic gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Gene that is masked or suppressed by the action of a gene at a different locus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/hypoxia-hypoxic-136">hypoxia</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An environmental condition in which the concentration of oxygen is lower than normally found in the environment. </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="I"><div class="padleft10px fleft bold px15">I</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> I kappa B transcription inhibitor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein that interacts with NF-kappaB in the cytoplasm, ensuring its partner does not homodimerize. When phosphorylated, I-kappaB releases NF-kappaB, which can then homodimerize and initiate downstream transcriptional events. </div> </div> </div> <div class="wrap"> <strong> Id protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A helix-loop-helix containing protein that can inhibit differentiation of muscle; protein that lacks the DNA binding domain common to this helix-loop-helix of proteins, consequently they heterodimerize to other transcription factors, and inhibit subsequent transcription. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> identical by descent </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Of two or more gene copies, being derived from a single gene copy in a specified common ancestor of the organisms that carry the copies. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> identical twins </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Twins that arise when a single egg fertilized by a single sperm splits into two separate embryos. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/idiogram-44">idiogram</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A diagram of chromosomal morphology, particularly depicting the banding patterns of specific chromosomes. </div> </div> </div> <div class="wrap"> <strong> immigration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The movement of individuals into a population or population area. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> immunogenicity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ability of a substance to elicit an immune response, such as the production of specific antibodies in an organism. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> immunoglobulin gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene that encodes the basic functional unit of an antibody, an immunoglobulin. </div> </div> </div> <div class="wrap"> <strong> immunoglobulins </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A class of proteins, with a characteristic structure, active as receptors and effectors in the immune system. <div class="px10"> © 2008 by Sinauer Associates, Inc. All rights reserved. Sadava, D. Life: the science of biology. 8th Edition.</div> </div> </div> </div> <div class="wrap"> <strong> immunohistochemistry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A set of methods for using an antibody to detect the presence and distribution of a protein in a tissue. </div> </div> </div> <div class="wrap"> <strong> imprinting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In genetics, the differential modification of a gene depending on whether it is present in a male or a female. In animal behavior, a rapid form of learning in which an animal comes to make a particular response, which is maintained for life, to some object or other organism. <div class="px10"> © 2008 by Sinauer Associates, Inc. All rights reserved. Sadava, D. Life: the science of biology. 8th Edition.</div> </div> </div> </div> <div class="wrap"> <strong> in situ hybridization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method used to determine the chromosomal location of a gene or other specific DNA fragment or the tissue distribution of an mRNA by using a labeled probe that is complementary to the sequence of interest. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/in-vitro-fertilization-ivf-193">in vitro fertilization</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process in which an oocyte is fertilized by sperm in a laboratory setting. </div> </div> </div> <div class="wrap"> <strong> in-frame deletion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Deletion of some multiple of three nucleotides, which does not alter the reading frame of the gene. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/inborn-error-of-metabolism-114">inborn error of metabolism</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Heritable disorder of an organism's biochemistry. </div> </div> </div> <div class="wrap"> <strong> inbred strain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of organisms that are homozygous at every locus. </div> </div> </div> <div class="wrap"> <strong> inbreeding </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The mating of closely related individuals. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> inbreeding coefficient </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Measure of inbreeding; the probability (ranging from 0 to 1) that two alleles are identical by descent. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> inbreeding depression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Decreased fitness arising from inbreeding; often due to the increased expression of lethal and deleterious recessive traits. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> inclusive fitness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The fitness of a gene or genotype as measured by its effect on the survival or reproduction of both the organism bearing it and the genes, identical by descent, borne by the organism's relatives. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/incomplete-dominance-149">incomplete dominance</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the phenotype of a heterozygote that is intermediate between the phenotypes of the two homozygotes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/incomplete-linkage-92">incomplete linkage</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Linkage between genes that exhibit some crossing over; intermediate in its effects between independent assortment and complete linkage. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> incomplete penetrance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a genotype that does not always express the expected phenotype. Some individuals possess the genotype for a trait but do not express the phenotype. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> incorporated error </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Incorporation of a damaged nucleotide or mismatched base pair into a DNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> independent assortment </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Independent separation of chromosome pairs in anaphase I of meiosis; contributes to genetic variation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> indigenous species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A species that is native to a give area if its presence was obtained by natural processes. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> indirect benefits </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Benefits gained by females from their choice of mate and affect the female through the fitness of her progeny. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> indirect development </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A life history consisting of a larval stage between embryo and adult stages. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> indirect fitness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Gene copies contributed by an individual to the next generation in the form of non-offspring, usually kin (e.g., siblings, nieces). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> indirect selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A covariance between a trait and fitness within a generation that is caused by a phenotypic correlation between that trait and another trait that experiences direct selection. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> individual selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of natural selection consisting of nonrandom differences among different genotypes (or phenotypes) within a population in their contribution to subsequent generations. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> induced mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Results from environmental agents, such as chemicals or radiation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> inducer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Substance that stimulates transcription in an inducible system of gene regulation; usually a small molecule that binds to a repressor protein and alters that repressor so that it can no longer bind to DNA and inhibit transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> inducible operon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Operon or other system of gene regulation in which transcription is normally off. Something must happen for transcription to be induced, or turned on. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> induction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stimulation of the synthesis of an enzyme by an environmental factor, often the presence of a particular substrate. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> industrial melanism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The increase in frequency of dark (melanic) pigmentation in insects as an adaptation to remain inconspicuous on surfaces darkened by soot from air pollution. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/infectious-disease-23">infectious disease</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An illness that can be passed from one individual to another. </div> </div> </div> <div class="wrap"> <strong> inflorescences </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> inhabitational </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One organisms living wholly or partly inside the other. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> inherit </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process by which offspring acquire genetic material from their parents. </div> </div> </div> <div class="wrap"> <strong> inheritance of acquired characteristics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Early notion of gene transmission proposing that acquired traits are passed to descendants. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> inhibition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The phenomenon of reducing or silencing neural activity by the action of an inhibitory neurotransmitter or conductance shunts within a cell. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> inhibition succession model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Where the species that arrive first dominate until a disturbance removes them. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> initiation codon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The codon in mRNA that specifies the first amino acid (fMet in bacterial cells; Met in eukaryotic cells) of a protein; most commonly AUG. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> initiation factor 1 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein required for the initiation of translation in bacterial cells; enhances the dissociation of the large and small subunits of the ribosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> initiation factor 2 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein required for the initiation of translation in bacterial cells; forms a complex with GTP and the charged initiator protein and then delivers the charged tRNA to the initiation complex. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> initiation factor 3 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein required for the initiation of translation in bacterial cells; binds to the small subunit of the ribosome and prevents the large subunit from binding during initiation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> initiator protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Binds to an origin of replication and unwinds a short stretch of DNA, allowing helicase and other single-strand binding proteins to bind and initiate replication. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> insertion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutation that occurs when one or more base pairs is added to a DNA sequence. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> insertion sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Simple type of transposable element found in bacteria and their plasmids that contains only the information necessary for its own movement. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> instinctive </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A behavior that is not learned, but rather stemming from impulse or unconscious behavior; can be based on physiological processes determined by genetic inheritance, and therefore common among individuals in a population. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/institutional-review-board-irb-247">institutional review board</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A specially constituted review body established or designated by an entity to protect the welfare of human subjects recruited to participate in biomedical or behavioral research. <div class="px10">http://www.hhs.gov</div> </div> </div> </div> <div class="wrap"> <strong> insulator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA sequence that blocks or insulates the effect of an enhancer; must be located between the enhancer and the promoter to have blocking activity; also may limit the spread of changes in chromatin structure. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> insulin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A hormone synthesized in islet cells of the pancreas that lowers glucose levels in the blood, by promoting the conversion of glucose into the storage material, glycogen. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> insurance hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> If more species are present (i.e., diversity is higher), then there is a greater chance that at least one of the species will maintain functioning during disturbance or stress, compensating for other species that experience declines. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> integrase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme that inserts prophage, or proviral, DNA into a chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/integrative-levels-of-organization-38">integrative levels of organization</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The idea that matter is arrayed in orders of increasing complexity, and that at each level, there are emergent properties such that the higher level cannot be reduced to the lower. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> inter-, intra- </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Prefixes meaning, respectively, .between. and .within.. For example, .interspecific. differences are differences between species and .intraspecific. differences are differences among individuals within a species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> inter-clonal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Between clones. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> interaction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> On any scale, the collision or interplay between entities that affects one or more of them, such as the merging of molecules into a compound, or the competition between species. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> intercalated </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes something that is inserted between two other things. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> intercalating agent </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chemical substance that is about the same size as a nucleotide and may become sandwiched between adjacent bases in DNA, distorting the three-dimensional structure of the helix and causing single-nucleotide insertions and deletions in replication. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> interchromosomal recombination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Recombination among genes on different chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> interdemic selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The third phase of the shifting balance theory, in which subpopulations (demes) at higher adaptive peaks export migrants to subpopulations at lower adaptive peaks, causing the lower-fitness subpopulations to evolve toward the higher peak. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/interference-73">interference</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Degree to which one crossover interferes with additional crossovers. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> intergenic suppressor mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Occurs in a gene (locus) that is different from the gene containing the original mutation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> interkinesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Period between meiosis I and meiosis II. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> intermediate disturbance hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Predicts that intermediate frequency or intensity of disturbance will maximize diversity. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> internal promoter </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Located within the sequences of DNA that are transcribed into RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> interphase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Period in the cell cycle between the cell divisions. In interphase, the cell grows, develops, and prepares for cell division. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> interspecific interactions </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Competition between members of different species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> interspersed repeat sequences </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Repeated sequences at multiple locations throughout the genome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> intrachromosomal recombination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Recombination among genes located on the same chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> intragenic mapping </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mapping the locations of mutations within a single locus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> intragenic suppressor mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Occurs in the same gene (locus) as the mutation that it suppresses. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> intrasexual selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Competition between members of the same sex (usually males) for access to mates. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> intraspecific competition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Competition for resources between individuals of two or more species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> intrinsic hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When expected proportions of individuals with the observed characteristics are calculated after the experiment is done using a specific piece of required data. </div> </div> </div> <div class="wrap"> <strong> intrinsic rate of natural increase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The potential per capita rate of increase of a population with a stable age distribution whose growth is not depressed by the negative effects of density. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> intrinsic rate of natural increase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The number of births minus the number of deaths per generation time. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> introduced species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A species that originated in a different region that becomes established in a new region, often due to deliberate or accidental release by humans. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> introgression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The permanent incorporation of genes from one species to another by repeated breeding of an interspecific hybrid with one of its parent species. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/intron-introns-67">intron</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Introns are non-coding sections of an RNA transcript, or the DNA encoding it, which are spliced out, or removed, before the RNA molecule is translated into a protein. </div> </div> </div> <div class="wrap"> <strong> invasion biology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of species that become invasive in a system and their impacts on the system they have invaded, as well as the remediation of such invasions. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> invasive </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Referring to a species or species which invade a habitat and are usually detrimental to the native species in that habitat. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> invasive species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Non-native species that increase rapidly in numbers and that have negative impacts on native species. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> inversion stock </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A line of organisms, usually Drosophila, that maintain a balancer chromosome. The presence of a specific balancer chromosome inhibits crossing over, allowing investigators to retain lines of animals that are heterozygous for a specific mutation without screening each generation for the phenotype. </div> </div> </div> <div class="wrap"> <strong> inverted repeats </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequences on the same strand that are inverted and complementary. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> iron-response element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Known as IRE, a short region found in mRNAs that forms a stem-loop structure and is bound by iron-response proteins; responds to presence of iron (high or low levels) that change mRNA stability and therefore increase (high iron) or decrease (low iron) translation. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> island model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The simplest model of gene flow, in which a proportion of migrants are exchanged between discrete subpopulations in each generation. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> isoaccepting tRNAs </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Different tRNAs with different anticodons that specify the same amino acid. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> isolating barrier </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genetically determined difference between populations that restricts or prevents gene flow between them. The term does not include spatial segregation by extrinsic geographic or topographic barriers. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> isometry for ontogenetic allometry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When an organ grows at the same rate as the rest of the body, a = 1, such an organ maintains a constant proportionate size (but not absolute size) throughout development; for static/evolutionary allometry, when an organ is proportionally the same size in larger and small individuals/species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> isotopes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Different forms of an element that have the same number of protons and electrons but differ in the number of neutrons in the nucleus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> isotopic labeling </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Use of radioisotopes to label biomolecules, enabling scientists to investigate them in cells or tissue. </div> </div> </div> <div class="wrap"> <strong> isozymes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Different forms of the same enzyme. Commonly used as genetic markers, especially between 1970 and 1990. The term isozyme is often used interchangeably with allozyme. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> iteroparity/polycarpy. </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Life histories characterized by reproducing repeatedly. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> iteroparous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pertaining to a life history in which individuals reproduce more than once. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="J"><div class="padleft10px fleft bold px15">J</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> J' of peiou </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An index used to describe species evenness, the distribution of abundance across species in a community. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> jump dispersal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When individuals of a species travel a relatively long distance to a new environment in which they did not previously occur. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Jun oncogene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A transcription factor that works with fos to initiate transcription of many genes, particularly in response to growth factor signaling. When c-Jun is constitutively expressed, it can cause cellular transformation. </div> </div> </div> <div class="wrap"> <strong> junctional diversity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Addition or deletion of nucleotides at the junctions of gene segments brought together in the somatic recombination of genes that encode antibodies and T-cell receptors. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="K"><div class="padleft10px fleft bold px15">K</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> K-selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of selection that occurs in an environment at or near carrying capacity, favoring a reproductive strategy in which few offspring are produced. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/karyotype-118">karyotype</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Picture of an individual organism's complete set of metaphase chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> key adaptation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An adaptation that provides the basis for using a new, substantially different habitat or resource. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> keystone species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species that have effects on communities that far exceed their abundance. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> kin selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of selection whereby alleles differ in their rate of propagation by influencing the impact of their bearers on the reproductive success of individuals (kin) who carry the same alleles by common descent. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> kin structure </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic relationships within a social group. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> kinetochore </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> On a chromosome centromere, a set of proteins that provide the point of attachment of spindle fibers. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Klinefelter syndrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Human condition in which cells contain one or more Y chromosomes along with multiple X chromosomes (most commonly XXY but may also be XXXY, XXXXY, or XXYY). Persons with Klinefelter syndrome are male in appearance but frequently possess small testes, some breast enlargement, and reduced facial and pubic hair; often taller than normal and sterile, most have normal intelligence. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> knockout </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organism in which the normal gene expression at a given locus (or sometimes multiple loci) has been disrupted. Therefore, this organism has little or no expression of the RNA or protein encoded by this gene. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/knockout-mouse-284">knockout mouse</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A knockout mouse is a laboratory mouse in which a gene or genes have been turned off or "knocked out." <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Kruppel transcription factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gap protein that has four tandemly repeated zinc finger domains. </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="L"><div class="padleft10px fleft bold px15">L</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> L1 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of three hybrid crosses used to detect linkage. In the absence of linkage, the progeny distribution in the F3 (F2 x F2) or L1 generation is identical to that in the F2 (F1 x F1) generation. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> L2 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of three hybrid crosses used to detect linkage. In the absence of linkage the progeny distribution in the L2 (F2 x P1) generation is identical to that in the B1 (F1 x P1) generation. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> L3 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of three hybrid crosses used to detect linkage. In the absence of linkage, the progeny distribution in the L3 (F2 x P2) generation is identical to that in the B2 (F1 x P2) generation. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> lagging strand </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA strand that is replicated discontinuously. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Lamarckism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The theory that evolution is caused by inheritance of character changes acquired during the life of an individual due to its behavior or to environmental influences. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> landrace </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Domesticated crop plant or livestock that has adaptations specific to the local environment in which it evolved. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> landscape ecolgy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of the pattern and interaction between ecosystems within a region of interest, and the way the interactions affect ecological processes, especially the unique effects of spatial heterogeneity on those interactions. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> large ribosomal subunit </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The larger of the two subunits of a functional ribosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> lariat </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A looped structure formed during pre-mRNA splicing, named for its resemblance to ropes used to catch livestock. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> lateral gene transfer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> See horizontal transmission. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> latitudinal gradient </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> For most taxa, as one moves away from the equator, the number of species declines. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> leader of mRNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The 5' untranslated region (UTR) of an mRNA molecule. </div> </div> </div> <div class="wrap"> <strong> leading strand </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In unwound DNA, the single strand that is replicated continuously, in contrast to its partner the lagging strand. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/leaky-mutation-168">leaky mutation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When a mutation does not cause a complete loss of function in the wild-type phenotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> lek </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An aggregation of males for the purpose of performing mating displays. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> leptotene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> First substage of prophase I in meiosis. In leptotene, chromosomes contract and become visible. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/lethal-allele-lethal-gene-lethal-mutation-lethality-146">lethal allele</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An allele (usually recessive) that causes virtually complete mortality, usually early in development. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> lethal effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Effects within a community that occur when predators consume lower trophic levels. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> leucine zipper </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A common name for a secondary structural motif in proteins that occurs when two alpha helices interact through leucine amino acids that are located at a specific position in the repeated sequence of amino acids that forms the two helices. The leucine residues interact along the hydrophobic core of the zipper. </div> </div> </div> <div class="wrap"> <strong> lianas </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any of various long-stemmed, woody vines that are rooted in the soil at ground level and use trees, as well as other means of vertical support, to climb up to the canopy in order to get access to well-lit areas of the forest. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> lichens </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Composite organisms consisting of a symbiotic association of a fungus with a photosynthetic partner. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> lifestyle </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A complex concept that includes an individual's environment, eating habits, and social behavior. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> light use efficiency </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The efficiency of using light to fix carbon (i.e., the proportion of light absorbed that is eventually converted to biomass). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> line </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A pure-breeding group of organisms. </div> </div> </div> <div class="wrap"> <strong> lineage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A series of ancestral and descendant populations through time; usually refers to a single evolving species, but may include several species descended from a common ancestor. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> lineage sorting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process by which each of several descendant species, carrying several gene lineages inherited from a common ancestral species, acquires a single gene lineage; hence, the derivation of a monophyletic gene tree, in each species, from the paraphyletic gene tree inherited from their common ancestor. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> linear </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a physical arrangement along a single line, such as a series of bases in a DNA sequence; in mathematics, a direct proportional relationship between two variables that does not change, regardless of scale. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> linear regression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A statistical technique of finding the best fitting straight line through a set of points representing joint values for two variables. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/linkage-51">linkage</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In genetics, refers to how two genes that are nearby to one another on the same chromosome are often inherited together <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> linkage disequilibrium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes the state of two genotypes at different loci being dependent, showing a correlation; does not require gene linkage. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> linkage equilibrium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The association of two alleles at two or more loci at the frequency predicted by their individual frequencies. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> linkage group </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Multiple genes located nearby on the same chromosome that are often inherited together. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> linkage map </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A map of gene loci for a specific chromosome based on linkage studies. </div> </div> </div> <div class="wrap"> <strong> linked genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genes that are often inherited together. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> linked loci </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Loci that are on the same chromosome and that show a recombination frequency less than 0.5. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> linker DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stretch of DNA separating two nucleosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> litterfall </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Undecomposed plant and animal material that accumulates on the ground. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> livestock </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Animals kept or raised for a specific purpose. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> local community </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A geographically defined community of place, a group of species living and interacting together. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> local extinction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When a species no longer resides in an area of habitat due to suboptimal conditions. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> local variation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Variation in secondary structure within a single molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> locus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The specific location of a gene or gene sequence along a chromosome; can be used to refer to the gene itself; plural is loci. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> locus control region </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cis-acting DNA element that is able to regulate gene expression from a specific region of DNA. The human beta-globin gene cluster is a leading example of genes regulated by a locus control region. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/lod-score-logarithm-of-odds-152">lod score</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Logarithm of the ratio of the probability of obtaining a set of observations, assuming a specified degree of linkage, to the probability of obtaining the same set of observations with independent assortment; used to assess the likelihood of linkage between genes from pedigree data. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> log-log scale </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A scale in which the numbers are proportional to their logarithms. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> log-odds ratio </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Logarithm of the ratio of the probability of obtaining a set of observations, assuming a specified degree of linkage, to the probability of obtaining the same set of observations with independent assortment; used to assess the likelihood of linkage between genes from pedigree data. <div class="px10">W. H. Freeman and Company</div> </div> </div> </div> <div class="wrap"> <strong> logistic equation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An equation describing the idealized growth of a population subject to a density-dependent limiting factor. As density increases, the rate of growth gradually declines until population growth stops. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> logistic population growth </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Population growth that levels off as the population size approaches carrying capacity, the ceiling of its growth. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> long interspersed element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Long DNA sequence repeated many times and interspersed throughout the genome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> longevity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Average or maximum lifespan of a cohort of organisms. <div class="px10">Judith Campisi</div> </div> </div> </div> <div class="wrap"> <strong> loss-of-function mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Causes the complete or partial absence of normal function. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> lotka-volterra models </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Simple model that tells us that predator and prey interactions have the potential to cause population cycles, and is useful in understanding and predicting predator-prey population cycles. The model was developed independently by Lotka (1925) and Volterra (1926). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> low copy repeat </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A term with variable meaning that is sometimes used synonymously with segmental duplication. It can denote a group of juxtaposed duplicons (duplication block), individual segmental duplication events, or individual duplicons. The term emphasizes the low copy number of repeats (2.50 copies) relative to most transposable elements. <div class="px10">Jeffrey A. Bailey & Evan E. Eichler</div> </div> </div> </div> <div class="wrap"> <strong> luciferin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The substrate for a basic luminescence assay. </div> </div> </div> <div class="wrap"> <strong> luciferin/luciferase reporter system </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A reporter gene assay system that allows investigators to measure biological activity after transfecting cells with the luciferase gene and conducting an experiment. Activity of the gene after experimental treatment is measured after adding luciferin and measuring luminescence. </div> </div> </div> <div class="wrap"> <strong> luminescence assay </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method to measure biological activity through a reporter construct that uses the luciferase-luciferin interaction for quantitation. </div> </div> </div> <div class="wrap"> <strong> Lyon hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proposed by Mary Lyon in 1961, this hypothesis proposes that one X chromosome in each female cell becomes inactivated (a Barr body) and suggests that which X becomes inactivated is random and varies from cell to cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> lysogenic cycle </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Life cycle of a bacteriophage in which phage genes first integrate into the bacterial chromosome and are not immediately transcribed and translated. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> lytic cycle </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Life cycle of a bacteriophage in which phage genes are transcribed and translated, new phage particles are produced, and the host cell is lysed. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="M"><div class="padleft10px fleft bold px15">M</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> M phase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Period of active cell division; includes mitosis (nuclear division) and cytokinesis (cytoplasmic division). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> M-phase promoting factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein functioning in the control of the cell cycle; consists of a cyclin combined with cyclin-dependent kinase (CDK). Active MPF stimulates mitosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> macroalgae </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Large algae (such as kelp), often living attached in dense beds in marine intertidal and subtidal zones. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> macroevolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A vague term, usually meaning the evolution of substantial phenotypic changes, usually great enough to place the changed lineage and its descendants in a distinct genus or higher taxon. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> magnetoreceptors </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Receptors in an organism that allow it to respond to the earth.s magnetic field. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> major gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene locus responsible for a large proportion of the phenotypic variation in a trait. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> major histocompatibility complex antigen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Belongs to a large and diverse group of antigens found on the surfaces of cells that mark those cells as self; encoded by a large cluster of genes known as the major histocompatibility complex. T cells simultaneously bind to foreign and MHC antigens. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> malignant tumor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consists of cells that are capable of invading other tissues. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> map density </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The number of markers per centimorgan on a genetic map. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> map distance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The distance between two markers on the same chromosome based on recombination frequency, usually measured in centimorgans (cM). <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> map-based sequencing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method of sequencing a genome in which sequenced fragments are ordered into contigs with the use of genetic or physical maps. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mapping-282">mapping</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA mapping describes a variety of different methods that can be used to describe the positions of genes. </div> </div> </div> <div class="wrap"> <strong> mapping population </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An experimental population constructed by crossing, designed for the production of a genetic map. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> mark-recapture study </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A technique in which animals are captured, marked, and released back into nature. The frequency at which they are recaptured is used to estimate survival or migration rates. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> marker </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An item used to label a location; a gene allele serving as a probe that predicts a certain phenotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Markovian MODEL </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Alternate name for a Markovian chain in which a sequence of random events where the current state solely depends on the previous state. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> mass extinction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A highly elevated rate of extinction of species, extending over an interval that is relatively short on a geological time scale (although still very long on a human time scale). <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> maternal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Of or relating to the female parent of an organism. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> maternal blood testing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Testing for genetic conditions in a human fetus by analyzing the blood of the mother. For example, the level of alpha-fetoprotein in maternal blood provides information about the probability that a fetus has a neural-tube defect. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> maternal effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A nongenetic effect on phenotype originating from the female parent, resulting from elements in the egg cytoplasm, or transmission of symbionts to offspring during development or postnatal contact, or nutritional conditions during development or after birth. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> maternal homolog </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The allele of a gene inherited from the female parent. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> mating type protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein that designates specific microorganisms (like yeast) as a specific "type" (equivalent to sex in higher organisms), allowing that type to mate with an individual haploid cell of the opposite mating type. </div> </div> </div> <div class="wrap"> <strong> matrix </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The majority of the landscape surrounding the patches (i.e., not the patches). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> maximum parsimony </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> See parsimony. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> mean annual biomass </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mean biomass of organisms in a population, group of populations, or trophic level (grams dry mass m to the -2) from samples taken throughout an entire year (e.g., from monthly samples). Other units may be used besides dry mass, such as carbon or the energy unit kilojoules). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> mean fitness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The arithmetic average fitness of all individuals in a population, usually relative to some standard. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> mean square </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The sums of squares divided by the degrees of freedom (n . 1). <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> mean statistic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Also called an average; the calculated sum of all measurements divided by the number of measurements; the statistic representing the center of a distribution of measurements in a set. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/medical-genetics-11">medical genetics</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of the natural history and etiology of diseases that are at least partially genetic in origin. </div> </div> </div> <div class="wrap"> <strong> medical treatment </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An intervention in an individual's health supervision that is designed to lessen the symptoms associated with a disease. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> megaspore </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the four products of meiosis in plants. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> megasporocyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In the ovary of a plant, a diploid reproductive cell that undergoes meiosis to produce haploid macrospores. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/meiosis-88">meiosis</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Meiosis is a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. </div> </div> </div> <div class="wrap"> <strong> meiosis I </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> First phase of meiosis. In meiosis I, chromosome number is reduced by half. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> meiosis II </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Second phase of meiosis. Events in meiosis II are essentially the same as those in mitosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> meiotic drive </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process resulting in more than 50% of gametes possessing one of the alleles from a heterozygoous genotype; indicates some bias in distribution during meiosis. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> melting temperature </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Midpoint of the melting range of DNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> memory cell </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Long-lived lymphocyte among the clone of cells generated when a foreign antigen is encountered. If the same antigen is encountered again, the memory cells quickly divide and give rise to another clone of cells specific for that particular antigen. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Mendelian population </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Group of interbreeding, sexually reproducing individuals. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Mendelian segregation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The production of equal numbers of gametes containing each allele from a heterozygous genotype. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mendelian-test-cross-320">Mendelian test cross</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A tool first described by Gregor Mendel to determine an unknown genotype; a cross between an organism with a homozygous recessive genotype an organism with an unknown genotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mendelian-trait-mendelian-characteristic-mendelian-phenotype-mendelian-174">Mendelian trait</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any trait controlled by a genetic locus that can be described by Mendelian principles of inheritance. </div> </div> </div> <div class="wrap"> <strong> meristic characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Characteristic whose phenotype varies in whole numbers, such as number of vertebrae. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> meroblastic cleavage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a cell division event during development that results in incomplete cleavage between daughter cells. Meroblastic cleavage is common in zygotes with large concentrations of yolk. </div> </div> </div> <div class="wrap"> <strong> merozygote </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial cell that has two copies of some genes.one copy on the bacterial chromosome and a second copy on an introduced F plasmid; also called partial diploid. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> meta-analysis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A statistical technique for jointly analyzing the results of many studies on the same topic. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> metabolic theory of ecology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Theory that aims to find the relationship between body mass and temperature and a variety of ecological phenomena. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> metabolism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In an organism, the total physical and chemical processes that support energy molecule production from nutrients, and the converse use of energy molecules to support cellular and organismal homeostasis. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> metacentric chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromosome in which the two chromosome arms are approximately the same length. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> metacommunity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Broadly defined as a collection of communities connected by dispersal. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> metallothionine promoter </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene promoter that is activated by heavy metals and oxidative stress. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/metaphase-249">metaphase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Metaphase is the third phase of mitosis, which is a process that separates the duplicated genetic material carried in the nucleus of a parent cell into two, identical daughter cells </div> </div> </div> <div class="wrap"> <strong> metaphase I </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of meiosis I. In metaphase I, homologous pairs of chromosomes align in the center of the cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> metaphase II </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of meiosis II. In metaphase II, individual chromosomes align on the metaphase plate. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> metaphase plate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Plane in a cell between two spindle poles. In metaphase, chromosomes align on the metaphase plate. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> metapopulation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A set of local populations, among which there may be gene flow and patterns of extinction and recolonization. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> metapopulation theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The theory that local populations of organisms undergo periodic colonization and extinction, but that these local populations are linked to other populations nearby by migration. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> metastasis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to cells that separate from malignant tumors and travel to other sites, where they establish secondary tumors. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/methylation-95">methylation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The addition of a methyl group (-CH3) to a molecule. Extensive methylation of cytosine in DNA is correlated with reduced transcription. <div class="px10"> © 2008 by Sinauer Associates, Inc. All rights reserved. Sadava, D. Life: the science of biology. 8th Edition.</div> </div> </div> </div> <div class="wrap"> <strong> metric trait </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A phenotypic character that is continuously distributed with more than just a few distinct types. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/microarray-202">microarray</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A microarray is a laboratory tool used to detect the expression of thousands of genes at the same time </div> </div> </div> <div class="wrap"> <strong> microclimates </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A climate of a relatively small area in which the temperature and moisture of that area can vary significantly from the greater region. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> microevolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A vague term, usually referring to slight, short-term evolutionary changes within species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> microhabitat </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A small, specialized habitat used by an organism. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/microrna-mirna-175">microRNA</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small RNAs, typically 21 or 22 bp in length, that are produced by cleavage of double-stranded RNA arising from small hairpins within RNA that is mostly single stranded. The miRNAs combine with proteins to form a complex that binds (imperfectly) to mRNA molecules and inhibits their translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/microsatellite-vntr-209">microsatellite</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic markers consisting of repeated units that are each 2 to 9 nucleotides long, arrayed in repeated sequences 10k to 100k nucleotides long. Sometimes they are also referred to as simple sequence repeats (SSR), simple sequence repeat polymorphisms (SSRP), or short tandem repeats (STR). <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> microspore </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Haploid product of meiosis in plants. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> microsporocyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Diploid reproductive cell in the stamen of a plant; undergoes meiosis to produce four haploid microspores. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> microtubule </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Long fiber composed of the protein tubulin; plays an important role in the movement of chromosomes in mitosis and meiosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> mid-domain effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Predicts a peak of diversity at the midpoint along any domain simply by the fact that the ranges of more species overlap in the middle of a domain (like a mountain or an island) than on the edges. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> mid-ocean gyres </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Large areas in the center of the oceans where nutrients are scarce, resulting in "marine deserts." <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> midparent </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The average phenotypic value of each pair of parents in an offspring- parent regression. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> mimicry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Similarity of certain characters in two or more species due to convergent evolution, when there is an advantage conferred by the resemblance. Common types include Batesian mimicry, in which a palatable mimic experiences lower predation because of its resemblance to an unpalatable model; and Mullerian mimicry, in which two or more unpalatable species enjoy reduced predation due to their similarity. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> minimal medium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Used to culture bacteria or some other microorganism; contains only the nutrients required by prototrophic (wild-type) cells.typically, a carbon source, essential elements such as nitrogen and phosphorus, certain vitamins, and other required ions and nutrients. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> minisatellites </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A class of repetitive sequences, 7100 nucleotides each, that span 500-20,000 bp, and are located throughout the genome, towards chromosome ends; typically longer in length than microsatellites (STRs). <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> minor gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A locus that determines a relatively small proportion of phenotypic variation in a trait. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> mismatch repair </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process that corrects mismatched nucleotides in DNA after replication has been completed. Enzymes excise incorrectly paired nucleotides from the newly synthesized strand and use the original nucleotide strand as a template when replacing them. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> missense mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Alters a codon in the mRNA, resulting in a different amino acid in the protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> mitigation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The reduction of intensity of any variable. In ecology, the legally mandated remediation for loss of protected species or ecosystems. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mitochondria-mitochondrion-130">mitochondria</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organelles in eukaryotic cells in which the citric acid cycle occurs and ATP is produced. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mitochondrial-dna-mtdna-240">mitochondrial DNA</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA in mitochondria; has some characteristics in common with eubacterial DNA and typically consists of a circular molecule that lacks histone proteins and encodes some of the rRNAs, tRNAs, and proteins found in mitochondria. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mitosis-cell-division-159">mitosis</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mitosis is a process of nuclear division in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter cells </div> </div> </div> <div class="wrap"> <strong> mitotic spindle </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Array of microtubules that radiate from two poles; moves chromosomes in mitosis and meiosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A representation of a complex system with a simpler one (noun); to simulate a complex system by creating a stand-in representation, and using that stand-in to test hypotheses about the complex system (verb). <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/model-organism-model-genetic-organism-139">model organism</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organism suitable for studying a specific trait, disease, or phenomenon, due to its short generation time, characterized genome, or similarity to humans; examples are a fly, fish, rodent or pig, whose biology is well known and accessible for laboratory studies. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> moderately repetitive DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA consisting of sequences that are from 150 to 300 bp in length and are repeated thousands of times. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> modern synthesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> See evolutionary synthesis. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> modified base </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Rare base found in some RNA molecules. Such bases are modified forms of the standard bases (adenine, guanine, cytosine, and uracil). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/modifier-gene-modifying-gene-265">modifier gene</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene that alters the phenotypic expression of another gene. </div> </div> </div> <div class="wrap"> <strong> modularity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ability of individual parts of an organism, such as segments or organs, to develop or evolve independently from one another; the ability of developmental regulatory genes and pathways to be regulated independently in different tissues and developmental stages. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> molecular chaperone </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Molecule that assists in the proper folding of another molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/molecular-clock-166">molecular clock</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The concept of measuring the time when lineages of organisms diverged, based on the assumtion that mutations occur at a steady rate over time. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> molecular genetics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of the chemical nature of genetic information and how it is encoded, replicated, and expressed. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> molecular motor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Specialized protein that moves cellular components. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> molecule </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The smallest unit of a chemical element that still retains properties of that element; composed of two or more atoms joined by covalent bonds or ionic attractions. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> monecious/hermaphroditic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species with no separate sexes. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> monoallelic expression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Expression of a gene from only one of two alleles in a diploid organism. </div> </div> </div> <div class="wrap"> <strong> monoecious </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the presence of both male and female reproductive structures in the same individual organism. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> monohybrid cross </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cross between two individuals that differ in a single characteristic.more specifically, a cross between individuals that are homozygous for different alleles at the same locus (AA _ aa); also refers to a cross between two individuals that are both heterozygous for two alleles at a single locus (Aa _ Aa). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> monomorphic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Having one form; refers to a population in which virtually all individuals have the same genotype at a locus. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> monomorphic species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The male and female, of the same species, look and behave in similar ways. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> monophyletic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a taxon, phylogenetic tree, or gene tree whose members are all derived from a common ancestral taxon. In cladistic taxonomy, the term describes a taxon consisting of all the known species descended from a single ancestral species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/monosomy-204">monosomy</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Absence of one of the chromosomes of a homologous pair. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> monozygote </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A zygote derived from a single egg. </div> </div> </div> <div class="wrap"> <strong> monozygotic twins </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Identical twins that arise when a single egg fertilized by a single sperm splits into two separate embryos. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> morgan </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> 100 map units. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> morphism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The condition of having a form, shape, or observable character. </div> </div> </div> <div class="wrap"> <strong> morphogen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Molecule whose concentration gradient affects the developmental fate of surrounding cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> mosaic evolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Evolution of different characters within a lineage or clade at different rates, hence more or less independently of one another. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mosaicism-mosaic-219">mosaicism</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Condition in which regions of tissue within a single individual have different chromosome constitutions. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mrna-messenger-rna-160">mRNA</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Also known as mRNA, the RNA molecule exported from the nucleus that carries genetic information for the amino acid sequence of a protein. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> mRNA stability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of the half-life of an mRNA molecule. </div> </div> </div> <div class="wrap"> <strong> mRNA surveillance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mechanisms for the detection and elimination of mRNAs that contain errors that may create problems in the course of translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> MspI endonuclease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A restriction endonuclease that cleaves at the recognition site C/CGG (with the / representing the cleavage site). When the 5'-C is methylated, MspI is inhibited. When the internal C is methylated, MspI can cleave normally. </div> </div> </div> <div class="wrap"> <strong> multifactorial characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Determined by multiple genes and environmental factors. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> multigene family </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Set of genes similar in sequence that arose through repeated duplication events; often encode different proteins. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> multiple 3' cleavage sites </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the presence of more than one 3' cleavage site on a single pre-mRNA, which allows cleavage and polyadenylation to take place at different sites, producing mRNAs of different lengths. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> multiple alleles </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Presence in a group of individuals of more than two alleles at a locus. Although, for the group, the locus has more than two alleles, each member of the group has only two of the possible alleles. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> multiplication rule </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> States that the probability of two or more independent events occurring together is calculated by multiplying the probabilities of each of the individual events. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mus-musculus-111">Mus musculus</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The genus and species of the common mouse. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> mutagen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any environmental agent that significantly increases the rate of mutation above the spontaneous rate. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> mutagenesis screen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method for identifying genes that influence a specific phenotype. Random mutations are induced in a population of organisms, and individual organisms with mutant phenotypes are identified. These individual organisms are crossed to determine the genetic basis of the phenotype and to map the location of mutations that cause the phenotype. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> mutant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cell or organism harboring a genetic mutation. </div> </div> </div> <div class="wrap"> <strong> mutant screen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An experiment used in "reverse genetics" to identify the loci responsible for specific phenotypes. Generally, the genetic material of wild-type parental organisms is altered (e.g., by treatment with a chemical mutagen) and organisms are allowed to breed to look for dominant phenotypes (F1) or recessive phenotypes (F2). </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mutation-8">mutation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any change in a genetic sequence, large or small. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> mutation frequency </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Number of mutations within a group of individual organisms. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/mutation-rate-131">mutation rate</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Frequency with which a gene changes from the wild-type to a specific mutant; generally expressed as the number of mutations per biological unit (i.e., mutations per cell division, per gamete, or per round of replication). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> mutation-selection balance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process in which removal of variation by selection is balanced by the input of new variation into the population by mutation. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> mutational meltdown </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process in which deleterious mutations are fixed due to random drift in small populations, which further decreases population size and thus increases the rate of fixation of deleterious mutations in a positive feedback loop. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> mutational variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The increment in the genetic variance of a phenotypic character caused by new mutations in each generation. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> mutualism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A symbiotic relation in which each of two species benefits by their interaction. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> mutualism/mutualisms </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The way in which two organisms interact biologically so that each derives a fitness benefit. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> mutualistic associatons </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Relationships where one organism shelters another, two organisms exchange resources, or tighter dependencies evolve, such as coevolved relationships between specialized pollinators and flowers. In some cases, species even cultivate others. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> mutualists/mutualistic partners </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species participating in an interaction that involves the exchange of goods or services between the two species where each receives a benefit from the interaction. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> mycorrhizae </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fungal mutualists associated with plant roots. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> MyoA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A myogenic transcription factor with a helix-loop-helix domain. </div> </div> </div> <div class="wrap"> <strong> myoblast </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An immature muscle cell. </div> </div> </div> <div class="wrap"> <strong> MyoD </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A transcription factor that can induce differentiation of embryonic muscle fibroblasts to myoblasts in culture. MyoD activates transcription of muscle-specific genes, including MyoA, MyoH, and itself. </div> </div> </div> <div class="wrap"> <strong> MyoH </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A myogenic transcription factor with a helix-loop-helix domain. </div> </div> </div> <div class="wrap"> <strong> myosin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the two major proteins of muscle; it makes up the thick filaments. <div class="px10"> © 2008 by Sinauer Associates, Inc. All rights reserved. Sadava, D. Life: the science of biology. 8th Edition.</div> </div> </div> </div> <div class="wrap"> <strong> myosin heavy chain gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The gene that encodes the part of the myosin protein that catalyzes ATP and faciliates motor activity. </div> </div> </div> <div class="wrap"> <strong> myrmecology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A branch of entomology; the scientific study of ants <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="N"><div class="padleft10px fleft bold px15">N</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> N-terminal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Also called the N-terminus, the specific end of a protein/polypeptide containing an amine group. This is distinct from the C-terminus, which is the opposite end of the polypeptide chain, and typically has a carboxyl group. The orientation of a polypeptide with two distinct ends originates in the translation process from the mRNA code, wherein synthesis of the protein begins with the N-terminus and ends with the C-terminus. <div class="px10">©Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> N-terminus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Also called N-terminal, the specific end of a protein/polypeptide containing an amine group. This is distinct from the C-terminus, which is the opposite end of the polypeptide chain, and typically has a carboxyl group. The orientation of a polypeptide with two distinct ends originates in the translation process from the mRNA code, wherein synthesis of the protein begins with the N-terminus and ends with the C-terminus. <div class="px10">©Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Nanog </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A transcription factor often associated with embryonic stem cells that is thought to be critical for maintaining the pluripotency of these cells. </div> </div> </div> <div class="wrap"> <strong> narrow-sense heritability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proportion of the phenotypic variance that can be attributed to additive genetic variance. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> natural language processing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Computer understanding, analysis, manipulation and/or generation of natural (human) language. <div class="px10">Bard, J. B. L. and Rhee, S. Y. Ontologies in biology: design, applications and future challenges. Nature Reviews Genetics 5, 213-222 (2004)</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/natural-selection-31">natural selection</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The differential survival and/or reproduction of classes of entities that differ in one or more characteristics. To constitute natural selection, the difference in survival and/or reproduction cannot be due to chance, and it must have the potential consequence of altering the proportions of the different entities. Thus, natural selection is also definable as a deterministic difference in the contribution of different classes of entities to subsequent generations. Usually, the differences are inherited. The entities may be alleles, genotypes or subsets of genotypes, populations, or, in the broadest sense, species. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> negative assortative mating </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mating between unlike individuals that is more frequent than would be expected on the basis of chance. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> negative control </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Gene regulation in which the binding of a regulatory protein to DNA inhibits transcription (the regulatory protein is a repressor). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/negative-selection-97">negative selection</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Form of natural selection in which rare, deleterious alleles are removed from a population. </div> </div> </div> <div class="wrap"> <strong> negative-strand RNA virus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA virus whose genomic RNA molecule carries the complement of the information for viral proteins. A negative-strand RNA virus must first make a complementary copy of its RNA genome, which is then translated into viral proteins. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> neo-Darwinism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The modern belief that natural selection, acting on randomly generated genetic variation, is a major, but not the sole, cause of evolution. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> neoclassical crosses </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The F2, F2 B1 and B2 are "classical" hybrid crosses. Neoclassical crosses were named by Collins (1971) and are all addition hybrid crosses. The are often used in estimating the number of segregating genes for quantitative traits. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> neofunctionalization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Divergence of duplicate genes whereby one acquires a new function. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> neopolyploid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A polyploid that has been produced by artificially inducing chromosome doubling. <div class="px10">Comai, L. The advantages and disadvantages of being polyploid. Nature Reviews Genetics 6, 836-846 (2005)</div> </div> </div> </div> <div class="wrap"> <strong> neoteny </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Heterochronic evolution whereby development of some or all somatic features is retarded relative to sexual maturation, resulting in sexually mature individuals with juvenile features. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> nested paternal half-sibling design </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A quantitative genetic design that is well-suited for estimating additive genetic variance, additive genetic correlation, and thus the G matrix. In this design, a few unique females (dams) are mated to each of a number of males (sires), and the traits of interest are measured on a few offspring from each dam. The data are analyzed with nested ANOVA. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> net primary productivity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The amount of energy primary producers (organisms that produce their own food from an external energy source such as the sun) capture and convert to tissue minus the amount they lose in cellular respiration. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> neuraminidase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type II integral membrane glycoprotein that facilitates virus release from cells by removing sialic acid from sialyloligosaccharides on the cell and viral surfaces. It is also a target of the protective immune response. <div class="px10">Kanta Subbarao & Tomy Joseph</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/neurofibromatosis-nf-261">neurofibromatosis</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An autosomal genetic disorder that results in the growth of tumors along different types of nerves. It can also impact the development of non-nervous system tissues, such as bones and skin. </div> </div> </div> <div class="wrap"> <strong> neurohormones </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Hormones produced and released by neurons. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> neutral alleles </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Traits or loci that have a negligible effect on fitness. A trait or locus is nearly neutral or effectively neutral if the mean phenotype or allele frequencies are determined more by random genetic drift than by selection. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> neutral equilibrium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An equilibrium in which a perturbed system attains a new state of equilibrium instead of returning to its original equilibrium state. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> neutral models </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Differences in relative abundance of any species are caused by historic patterns of abundance and dispersion; these species have equal effects on biodiversity. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> neutral mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Changes the amino acid sequence of a protein but does not alter the function of the protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/neutral-theory-of-evolution-141">neutral theory of evolution</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Neutral theory claims that the overwhelming majority of evolutionary changes at the molecular level are not caused by selection acting on advantageous mutants, but by random fixation of selectively neutral or very nearly neutral mutants through the cumulative effect of sampling drift (due to finite population number) under continued input of new mutations. <div class="px10">Matoo Kimura. (1991). The neutral theory of molecular evolution: a review of recent evidence. Jpn J Genet 66, 367-386.</div> </div> </div> </div> <div class="wrap"> <strong> neutral theory of species diversity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A 2001 theory by Stephen Hubbell proposing that species co-occur for a long time periods because of competitive equivalence. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> neutral-mutation hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proposes that much of the molecular variation seen in natural populations is adaptively neutral and unaffected by natural selection. Under this hypothesis, individuals with different molecular variants have equal fitnesses. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> newborn screening </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Testing newborn infants for certain genetic disorders; done most commonly for phenylketonuria and other metabolic diseases that can be prevented by early treatment or intervention. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> niche </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The particular set of combined conditions that are habitable for a species, and define its status within an ecological community. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> niche space </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The multidimensional space encompassing suitable conditions for all factors which represents the conditions under which an individual, population, or species will persist. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> nitrogen deposition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The input of reactive nitrogen forms from the atmosphere to the land. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> nitrogenous base </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Nitrogen-containing base that is one of the three parts of a nucleotide. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> NMR specroscopy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A powerful method for determining the structure of organic compounds. </div> </div> </div> <div class="wrap"> <strong> non-coding rnas </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An RNA molecule that is not translated into a protein. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> non-equilibrium view </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Whether a system really tend toward steady state at all and emphasizes that disturbance in time and space constantly interact to influence the ecology and evolutionary trajectories in the ecosystems. This more current framework focuses attention on the importance of variation and transient dynamics rather than expecting steady states. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> non-functional dna </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Segments of DNA with no known biological function or importance. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> non-lethal effect/non-consumptive effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Effect within a community that occur when prey react to predators by altering their behavior, morphology, and/or habitat selection. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> nonadditive genetic variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Variance caused by dominance and interaction. Mathematically defined as dominance variance plus epistatic variance. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> nonallelic homologous recombination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Homologous recombination between paralogous sequences (for example, segmental duplication and repetitive sequence); a major mechanism of recurrent rearrangements, also known as unequal crossing-over. <div class="px10">Jeffrey A. Bailey & Evan E. Eichler</div> </div> </div> </div> <div class="wrap"> <strong> nonautonomous element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transposable element that cannot transpose on its own but can transpose in the presence of an autonomous element of the same family. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> noncoding RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA in a cell that does not encode a protein. </div> </div> </div> <div class="wrap"> <strong> nondisjunction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Failure of homologous chromosomes or sister chromatids to separate in meiosis or mitosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonhistone chromosomal protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of a heterogeneous assortment of nonhistone proteins in chromatin. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonlinear allometries </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When the scaling relationship between organ and body is not linear on a log-log scale. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> nonoverlapping genetic code </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the fact that generally each nucleotide is a part of only one codon and codes for only one amino acid in a protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonparametric analysis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Analysis widely used for studying populations that take on a ranked order (such as movie reviews receiving one to four stars). The use of this analysis may be necessary when data have a ranking but no clear numerical interpretation, such as when assessing preferences. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> nonreciprocal translocation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Movement of a chromosome segment to a nonhomologous chromosome or region without any (or with unequal) reciprocal exchange of segments. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonrecombinant gamete </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Contains only original combinations of genes present in the parents. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonrecombinant progeny </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Possesses the original combinations of traits possessed by the parents. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonreplicative transposition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of transposition in which a transposable element excises from an old site and moves to a new site, resulting in no net increase in the number of copies of the transposable element. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonsegregating generations </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Generation in which there is one genotype (excluding sex chromosomes). These are the P1, P2, F1, and F1R generations. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> nonsense codon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Codon in mRNA that signals the end of translation; also called stop codon or termination codon. There are three common nonsense codons: UAA, UAG, and UGA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/nonsense-mutation-228">nonsense mutation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A nonsense mutation is a genetic mutation in a DNA sequence that results in a shorter, unfinished protein product. </div> </div> </div> <div class="wrap"> <strong> nonsense-mediated mRNA decay </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process that brings about the rapid elimination of mRNA that has a premature stop codon. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonstop RNA decay </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mechanism in eukaryotic cells for dealing with ribosomes stalled at the 3' end of an mRNA that lacks a termination codon. A protein binds to the A site of the stalled ribosome and recruits other proteins that degrade the mRNA from the 3' end. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nonsynonymous substitution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A replacement substitution or a point mutation that results in a codon that is translated into a different amino acid and thus a different final protein product. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> nontemplate strand </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The DNA strand that is complementary to the template strand; not ordinarily used as a template during transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nontransmissible disease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A disorder that cannot be passed between organisms. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/norm-of-reaction-119">norm of reaction</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Range of phenotypes produced by a particular genotype in different environmental conditions. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> normal distribution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A probability distribution that peaks in the center and is symmetrical, forming a bell-shape; commonly occurring among observations of natural phenomena; important in statistics and biology; the expected probability distribution when many small independent effects combine. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> normoxic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The state of the environment in which oxygen concentration is at normal levels. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/northern-blot-287">Northern blot</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A Northern blot is a laboratory method used to detect specific RNA molecules from a mixture of RNA molecules </div> </div> </div> <div class="wrap"> <strong> Northern blotting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process by which RNA is transferred from a gel to a solid support such as a nitrocellulose or nylon filter. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nuclear envelope </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Membrane that surrounds the genetic material in eukaryotic cells to form a nucleus; segregates the DNA from other cellular contents. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nuclear factor-kappa B </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A family of dimeric transcription factors that regulate a variety of cellular signaling events. NF-kappaB monomers are held inactive via binding to an inhibitory protein called I-kappaB. When I-kappaB is phosphorylated, the interaction with NF-kappaB is released and allowed to dimerize, thus promoting its interaction with DNA. </div> </div> </div> <div class="wrap"> <strong> nuclear lamina </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The inner surface of the nuclear envelope, composed of a network of lamin filaments and associated proteins. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> nuclear matrix </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Network of protein fibers in the nucleus; holds the nuclear contents in place. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/nuclear-pore-279">nuclear pore</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The nuclear pore is a protein-lined channel in the nuclear envelope that regulates the transportation of molecules between the nucleus and the cytoplasm </div> </div> </div> <div class="wrap"> <strong> nuclear pre-mRNA introns </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Class of introns in protein-encoding genes that reside in the nuclei of eukaryotic cells; removed by spliceosomal-mediated splicing. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nuclear run-off assay </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method for measuring gene transcription at a specific time that involves incorporating radioactive nucleotides into growing mRNA chains combined with Northern blotting. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/nucleic-acid-274">nucleic acid</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A nucleic acid is a long molecule made up of smaller molecules called nucleotides </div> </div> </div> <div class="wrap"> <strong> nucleoid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial DNA confined to a definite region of the cytoplasm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nucleolytic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzymatic activity that describes the ability to cleave nucleic acid. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> nucleoside </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Ribose or deoxyribose sugar bonded to a base. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/nucleosome-nucleosomes-30">nucleosome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A nucleosome is a section of DNA that is wrapped around a core of proteins </div> </div> </div> <div class="wrap"> <strong> nucleotide </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A nitrogenous base attached to a sugar; a component of nucleic acids. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> nucleotide substitution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A point mutation where one base pair is replaced by another. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> nucleotide-excision repair </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA repair that removes bulky DNA lesions and other types of DNA damage. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/nucleus-59">nucleus</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Space in eukaryotic cells that is enclosed by the nuclear envelope and contains the chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> null allele </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An allele that does not yield a protein product, or whose phenotypic effect is masked. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/null-hypothesis-41">null hypothesis</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The statistical hypothesis that states that there will be no differences between observed and expected data. </div> </div> </div> <div class="wrap"> <strong> null model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A hypothesis used for statistical testing that states random processes create observed patterns and compared to alternative hypotheses. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> nullisomy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Absence of both chromosomes of a homologous pair (2n - 1). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> NusA factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein subunit of bacterial RNA polymerase that facilitates the termination of transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> nutrient cycling </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The cycling of nutrients between organisms and the physical environment. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="O"><div class="padleft10px fleft bold px15">O</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> obligate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Required, or by necessity (adj.); to force (verb) <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> obligate slave-maker </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of social parasitism in ants whereby the colonies require slave ants in order to survive. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> observational variance components </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The sub-components of phenotypic variance due to mating design. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> obsessive-compulsive disorder </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An anxiety disorder characterized by repeated, upsetting thoughts called obsessions and by repetitive behaviors aimed at reducing the obsessions. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> occipital cortex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The five outermost cortical tissue layers located in the caudal-most location of mammalian brain, the occipital lobe. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> oceanic islands </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Islands that have emerged from the sea floor in the ocean. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Oct4 transcription factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A POU family homeodomain containing transcription factor. </div> </div> </div> <div class="wrap"> <strong> offspring </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The children resulting from a cross between two parents. </div> </div> </div> <div class="wrap"> <strong> offspring-parent regression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A regression analysis wherein the slope of the regression line reflects heritability of a trait; created by collected data on organisms and their offpsring. Supports analyses of additive genetic variance, additive genetic correlation, and the G matrix. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Okazaki fragment </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Short stretch of newly synthesized DNA; produced by discontinuous replication on the lagging strand, these fragments are eventually joined together. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> old field </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Lands that are cultivated or grazed and them abandoned. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> oligogenic trait </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait produced by only a few genes. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> oligonucleotide </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A short polymer of nucleotides, between 2 and 50 nucleotides long, used in the study of gene mechanism; in parlance, sometimes referred to as an "oligo." <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> oligonucleotide backbone </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Part of an oligonucleotide that holds the nucleic acid bases together. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> oligonucleotide-directed mutagenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method of site-directed mutagenesis that utilizes an oligonucleotide to introduce a mutant sequence into a DNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> omnivore </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organism that relies on both animal and non-animal organisms, or even decaying matter, for food and nutrients. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> oncogene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Dominant-acting gene that stimulates cell division, leading to the formation of tumors and contributing to cancer; arises from mutated copies of a normal cellular gene (protooncogene). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> one gene, one enzyme hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Idea proposed by Beadle and Tatum that each gene encodes a separate enzyme. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> one gene, one polypeptide hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Modification of the one gene, one enzyme hypothesis; proposes that each gene encodes a separate polypeptide chain. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> ontogenetic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Allometry the relationship of x and y that are traits measured in the same individual through developmental time. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ontogeny </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The complete developmental history of an organism from zygote to adult. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ontology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A hierarchical organization of concepts, typically used to denote 'more-general-than' and/or 'part-of' relationships. <div class="px10">Yandell, M. D. and Majoros, W. H. Genomics and natural language processing. Nature Reviews Genetics 3, 601-610 (2002)</div> </div> </div> </div> <div class="wrap"> <strong> oogenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Egg production in animals. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> oogonium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Diploid cell in the ovary; capable of undergoing meiosis to produce an egg cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> open reading frame </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Continuous sequence of DNA nucleotides that contains a start codon and a stop codon in the same reading frame; is assumed to be a gene that encodes a protein but, in many cases, the protein has not yet been identified. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> operator sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The DNA sequence in the operon of a cell; binding to this sequence by a regulator protein changes gene transcription. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/operon-232">operon</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The set of genes, together with promoter sequence and operator sequence, that control the transcription of a gene; first discovered in prokaryotes, now known to be present in eukaryotes as well. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> optimal foraging theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Relates the costs of moving among different habitat patches to habitat quality and the distances separating patches. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> organism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of life as an individual entity. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> origin of replication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Site where DNA synthesis is initiated. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> origin position </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The location on a gel where a sample is added, marking the origin of the path of migration during electrophoresis. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> orthologous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes homologous genes in different species that originate from the same ancestral line. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> outbreeding depression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Occurs when offspring from crosses between populations have lower fitness than the offspring from crosses within each population. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> outcrossing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mating between unrelated individuals that is more frequent than would be expected on the basis of chance. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> outgroup </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In a group of taxa, the group that diverged first. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ovalbumin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The main protein in egg whites. </div> </div> </div> <div class="wrap"> <strong> overdominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A condition where the heterozygote is better adapted than either homozygote. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> overstory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The larger, taller trees that of a forest that overtop and shade younger and smaller trees and shrubs. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> oviduct </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An anatomical structure in mammals, usually tube-shaped, through which ova travel, either to a uterus or outside the body. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> oviparous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes an animal that lays eggs. </div> </div> </div> <div class="wrap"> <strong> ovum </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Final product of oogenesis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> ozone layer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A layer of ozone around the earth protects the life on earth from the sun.s harmful ultraviolet rays. The layer is about ten to thirty miles above the earth.s surface. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="P"><div class="padleft10px fleft bold px15">P</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> p - element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A transposable DNA element in Drosophila that is frequently used to facilitate insertional mutagenesis for genetic screens. </div> </div> </div> <div class="wrap"> <strong> P generation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> First set of parents in a genetic cross. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> p-arm </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The short arm of a chromosome. </div> </div> </div> <div class="wrap"> <strong> pachytene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In meiosis, the third substage of prophase I; the synaptonemal complex forms during this substage. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> paedomorphosis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The resemblance of the adult morphology to the morphology of the ancestral juvenile. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> pain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A subjective characterization of sensation associated with physical damage to the body. The perception of pain is protective; it provides feedback that allows the avoidance of further injury or of dangerous situations. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> pair-rule genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Set of segmentation genes in fruit flies that define regional sections of the embryo and affect alternate segments. Mutations in these genes often cause the deletion of every other segment. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> paleoecology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Using data from fossils to reconstruct ecosystems of the past. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> palindrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence of nucleotides that reads the same on complementary strands; inverted repeats. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pancreas </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A large gland located behind the stomach that secretes insulin and glucagon (an endocrine function) and digestive enzymes (an exocrine function). <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/pandemic-flu-197">pandemic flu</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An influenza virus of a new subtype to which the general population has little or no immunity that causes disease in humans and spreads efficiently from person to person, causing community-wide outbreaks and resulting in a global outbreak of influenza. <div class="px10">Kanta Subbarao & Tomy Joseph</div> </div> </div> </div> <div class="wrap"> <strong> pangenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Early concept of heredity proposing that particles carry genetic information from different parts of the body to the reproductive organs. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> panmictic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A breeding population where mating is random. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> panmixia </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Random mating within a population. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> paracentric inversion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromosome inversion that does not include the centromere in the inverted region. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> parallel evolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The independent development of similar adaptive features. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> paralogous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes two (or more) genes located at different locations in the genome of an organism that are related, based on sequence similarity, suggesting they derived from a common ancestor gene earlier in their evolution via mutation or genetic drift. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> parapatric </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Relating to populations whose biogeography has a narrow contact zone. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> paraphyletic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A phylogeny that only includes a portion of descendants from a certain ancestor. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> parasitism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Situation in which an individual organism, the parasite, consumes nutrients from another organism, its host, resulting in a decrease in fitness to the host as a result of the interaction. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> parasitoid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Larval stage of an insect that consumes and eventually kills its host. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> parental effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The effect of parents on traits in progeny not due to genetic effects. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> parental investment </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The parental devotion of resources to current progeny at the expense of potential future progeny. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> parental line </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The line used for the first generation of a genetic cross; usually a pure-breeding stain. </div> </div> </div> <div class="wrap"> <strong> parsimony </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The principle of succinctness in problem solving. A rule that states the best theoretical phylogeny is the one that proposes the least number of changes. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> parthenogenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Development of an embryo from an unfertilized ova. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> partial diploid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial cell that possesses two copies of genes, including one copy on the bacterial chromosome and the other on an extra piece of DNA (usually a plasmid); also called merozygote. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> partial dominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When one trait is not fully dominant over another; here, one can see a "mixing" of the characteristics. Incomplete dominance and codominance are two types of partial dominance. </div> </div> </div> <div class="wrap"> <strong> particulate inheritance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The model described by Mendel which suggested that transmission of inherited traits occurs through distinct units (particles) in contrast to a blending of characters from each parent. </div> </div> </div> <div class="wrap"> <strong> passive restoration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Allowing natural succession to occur in an ecosystem after removing a source of disturbance.Â The recovery of the deciduous forests in the eastern United States after the abandonment of agriculture is a classic. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Patau syndrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Characterized by severe mental retardation, a small head, sloping forehead, small eyes, cleft lip and palate, extra fingers and toes, and other disabilities; results from the presence of three copies of chromosome 13 (trisomy 13). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> patch </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An area of an ecosystem differing from its surroundings, often the smallest ecologically distinct feature in a landscape mapping and classification system. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> patch-corridor-matrix concept </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Landscapes are conceptualized and analyzed as mosaics of discrete patches recognizing the three major elements that can be recognized in the landscape. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/patent-215">patent</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A property right granted by the government of the United States of America to an inventor .to exclude others from making, using, offering for sale, or selling the invention throughout the United States or importing the invention into the United States. for a limited time in exchange for public disclosure of the invention when the patent is granted. <div class="px10">www.uspto.gov</div> </div> </div> </div> <div class="wrap"> <strong> paternal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Of or relating to the male parent of an offspring. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> paternal homolog </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An allele of a locus that was inherited from the genetic contribution of the father. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/paternity-26">paternity</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fatherhood; the state of being a father. Establishing who is the father of an offspring. </div> </div> </div> <div class="wrap"> <strong> path integration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ability to remember the distances and directions traveled, to sum them, and then to calculate their return path. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> pathogens </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Parasites that cause disease or death to their host organism. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> pattern formation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Clumped dispersal patterns. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> peak shift </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method by which a population navigates an adaptive landscape by moving from one peak (local maximum of fitness) through a valley (lower fitness) to another peak. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> pedigree </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pictorial representation of a family history outlining the inheritance of one or more traits or diseases. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/penetrance-69">penetrance</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Penetrance is a measure of the proportion of individuals in a population who carry a specific gene and express the related trait </div> </div> </div> <div class="wrap"> <strong> pentaploidy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the possession of five haploid sets of chromosomes (5n). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/peptide-317">peptide</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A series of two or more amino acids connected by peptide bonds. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> peptide bond </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Covalent chemical bond between two amino acids; connects the carboxyl group of one amino acid to the amino group of another. A series of peptide bonds and amino acids form a protein. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> peptidyl site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of three sites in a ribosome occupied by a tRNA in translation. In the elongation stage of protein synthesis, tRNAs move from the aminoacyl (A) site into the P site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> peptidyl transferase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Activity in the ribosome that creates a peptide bond between two amino acids. Evidence suggests that this activity is carried out by one of the RNA components of the ribosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> perennating organ </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Tissues that give rise to new growth the following season, and are therefore sensitive to climatic conditions. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> pericentric inversion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromosome inversion that includes the centromere in the inverted region. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> peripatric </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Referring to populations whose biogeography is adjacent but with no overlap. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> peripatric speciation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The reproductive isolation of a small population that has separated from a larger group; a consequence of the sensitivity of small populations to the effects of genetic drift. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> peripheral populations </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The population of a species that resides towards the margin of its habitat <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> permanent inquilines </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An animal that completely lives in the nest, burrow, or colony of another species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> pesticide rotation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Alternating among pesticides with different modes of action to alleviate resistance. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacteriophage; a type of virus that infects bacteria. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phanerophytes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Plants with their perennating organs greater than 0.5 meters above the ground (normally woody perennials). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/pharmacogenomics-pharmacogenomic-pharmacogenetic-40">pharmacogenomics</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The use of genetic information to guide drug prescribing. </div> </div> </div> <div class="wrap"> <strong> phenetic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Referring to classification based on observable traits (phenotype). <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phenocopy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phenotype that is produced by environmental effects and is the same as the phenotype produced by a genotype. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> phenology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The timeframe for any seasonal biological phenomena. The study of the relationship between climate and the timing of ecological events such as the date and emergence of leaves and flowers, the first flight of butterflies and the first appearance of migratory birds. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/phenotype-phenotypes-35">phenotype</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The observable physical properties of an organism, such as the organism's appearance, development, and behavior. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phenotypic adaptive landscape </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A graphical representation of the fitness of phenotypic traits where height represents fitness. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phenotypic correlation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Degree of association of traits calculated by measuring pairs of observable characteristics in individuals within a population. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phenotypic plasticity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The capacity of an organism to express a different range of phenotypes in response to environmental changes. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phenotypic value </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The combined effect of genotypic value and environmental effect resulting in the measurable observed character trait. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phenotypic variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Measures the degree of phenotypic differences among a group of individuals; composed of genetic, environmental, and genetic-environmental interaction variances. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/phenylketonuria-pku-66">phenylketonuria</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic disease characterized by mental retardation, light skin, and eczema; caused by mutations in the gene that encodes phenylalanine hydroxylase (PAH), a liver enzyme that normally metabolizes the amino acid phenylalanine. When the enzyme is defective, phenylalanine is not metabolized and builds up to high levels in the body, eventually causing mental retardation and other characteristics of the disease. The disease is inherited as an autosomal recessive disorder and can be effectively treated by limiting phenylalanine in the diet. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/phosphate-backbone-273">phosphate backbone</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The sugar-phosphate backbone forms the structural framework of nucleic acids, like DNA and RNA, and is composed of alternating sugar and phosphate groups. </div> </div> </div> <div class="wrap"> <strong> phosphate group </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A phosphorus atom attached to four oxygen atoms; one of the three components of a nucleotide. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> phosphodiester </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Molecule containing R.O.P.O.R, in which R is a carbon-containing group, O is oxygen, and P is phosphorus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> phosphodiester linkage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phosphodiester bond connecting two nucleotides in a polynucleotide strand. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> phosphorothioate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A phosphate with one oxygen replaced with a sulfur; this can also refer to an oligo with phosphorothioate linkages. <div class="px10">Jon Moulton</div> </div> </div> </div> <div class="wrap"> <strong> phosphorylation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The enzymatic addition of a phosphate group to a protein. </div> </div> </div> <div class="wrap"> <strong> photoautotrophs </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that are able to synthesize their own food from collected light energy through photosynthesis. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> photosynthesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A biochemical process of a cell or a tissue that captures light energy and uses it to convert carbon dioxide and water into complex organic molecules; the resulting organic molecules can be used as as nutrients or to build biomass. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> photosynthetic capability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> How much energy an organism is able to capture from the sun to, through a series of chemical steps, synthesize sugars; how much energy an organism is able to convert from light energy to chemical energy. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> phylogenetic distance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of the degree of separation between two organisms or their genomes on an evolutionary scale, usually expressed as the number of accumulated DNA or RNA sequence changes, number of years, or number of generations. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phylogenetic profile </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The presence-and-absence pattern of genes in different species, which may be used to infer gene function. A presence-and-absence pattern that is the same in different organisms suggests that the genes may be functionally related. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> phylogenetic relationship </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In evolutionary past, the relative times that two organisms or species shared a common ancestor; indicated by the relative position of a different species on a phylogenetic tree. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> phylogenetic species concept </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of organisms that share a common ancestor that is not shared by other groups of organisms. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/phylogenetic-tree-25">phylogenetic tree</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Graphical representation of the evolutionary connections between organisms or genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/phylogeny-80">phylogeny</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The history of descent of a group of taxa such as species from their common ancestors, including the order of branching and sometimes the absolute times of divergence; also applied to the genealogy of genes derived from a common ancestral gene. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> physical distance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The number of nucleotides between two loci. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/physical-linkage-241">physical linkage</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phenomenon in which two genes are located on the same chromosome. </div> </div> </div> <div class="wrap"> <strong> physical map </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Map of physical distances between loci, genetic markers, or other chromosome segments; measured in base pairs. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pilus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Extension of the surface of some bacteria that allows conjugation to take place. When a pilus on one cell makes contact with a receptor on another cell, the pilus contracts and pulls the two cells together. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pioneer community </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A community composed of the initial inhabitants (early seral stage). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Pioneer species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species that colonize early in a vegetational succession; pioneer species possess characteristics like rapid growth, the production of copious, small, easily dispersed seed, and the ability to germinate and establish themselves on open sites. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> planktonic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes an aquatic organism that is passively-floating and forms the foundation of the aquatic food chain. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> plaque </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Clear patch of lysed cells on a continuous layer of bacteria on the agar surface of a petri plate. Each plaque represents a single original phage that multiplied and lysed many cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/plasmid-plasmids-28">plasmid</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A plasmid is a small, circular, double-stranded DNA molecule, which is distinct from chromosomal DNA </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/pleiotropy-176">pleiotropy</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The phenomenon in which one locus affects more than one phenotypic trait, causing a genetic correlation. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> ploidy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The number of complete sets of chromosomes in an organism. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/point-mutation-3">point mutation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A change in a single nucleotide in a DNA sequence. See also transition, transversion. </div> </div> </div> <div class="wrap"> <strong> pollen </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Granules containing the male gametophyte of seed plants. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> poly(A) addition sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An AAUAAA sequence in the 3' end of a growing mRNA that binds to several proteins that signal the end of the templated molecule, cleavage of the mRNA molecule, and subsequent polyadenylation. </div> </div> </div> <div class="wrap"> <strong> poly(A) tail </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> String of adenine nucleotides added to the 3' end of a eukaryotic mRNA after transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> poly(A)-binding protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Binds to the poly(A) tail of eukaryotic mRNA and makes the mRNA more stable. There are several types of PABPs, one of which is PABII. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/poly-a-tail-276">poly-A tail</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The poly-A tail is a long chain of adenines nucleotides that is added to a messenger RNA (mRNA) molecule during RNA processing to increase the stability of the mRNA molecule </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/polycystic-kidney-disease-pkd-58">polycystic kidney disease</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An inherited kidney disorder in which multiple cysts form on the kidneys, causing them to become enlarged; abbreviated as PKD. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/polygenic-polygenic-characteristic-polygenic-trait-90">polygenic</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a trait under the control of multiple genes. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/polymerase-chain-reaction-pcr-110">polymerase chain reaction</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An automated method for synthesizing many copies of a specific fragment of DNA by repeated rounds of DNA replication; abbreviated as PCR. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> polymorphic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pertaining to more than one common allele or trait. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/polymorphism-86">polymorphism</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The existence within a population of two or more genotypes, the rarest of which exceeds some arbitrarily low frequency (say, 1 percent); more rarely, the existence of phenotypic variation within a population, whether or not genetically based. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> polynucleotide strand </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Series of nucleotides linked together by phosphodiester bonds. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> polypeptide </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chain of amino acids linked by peptide bonds; also called a protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> polyphenism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When different environmental conditions result in differing phenotypes from the same genotype. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> polyphyletic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A family or relational grouping of taxa where members do not share all ancestors in common. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> polyploid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Containing more than two complete sets of chromosomes. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> polyribosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Messenger RNA molecule with several ribosomes attached to it. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> polysomy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The occurrence of an extra chromosome. </div> </div> </div> <div class="wrap"> <strong> polytene chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Giant chromosome in the salivary glands of Drosophila melanogaster; each polytene chromosome consists of a number of DNA molecules lying side by side. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pool habitat </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A stream location with constant stream bottom height. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> population </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of the same species in the same area that have the potential to interbreed with one another. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/population-bottleneck-300">population bottleneck</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A population bottleneck is an event that drastically reduces the size of a population </div> </div> </div> <div class="wrap"> <strong> population differentiation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The genetic differences between populations or between a population and an ancestral group. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> population ecology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The study of individual populations (of a single species), including their birth, death, and growth rates in numbers and their growth rates of individual mass and population biomass; also includes their spatial distributions and rates of movement (immigration, emigration). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> population genetics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Study of the genetic composition of populations (groups of individuals of the same species) and how a population's collective group of genes changes through time. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> portfolio effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> If the abundance of different species fluctuates independently, or at least out of phase with one another, then these fluctuations will average each other out, leading to less variation over time in a diverse assemblage. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> position effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Dependence of the expression of a gene on the gene's location in the genome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> positional cloning </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method that allows for the isolation and identification of a gene by examining the cosegregation of a phenotype with previously mapped genetic markers. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> positive allometry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> For ontogenetic allometry, when the organ has a higher growth rate than the body as whole, a > 1; for static/evolutionary allometry, when an organ is proportionally larger in larger individuals/species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> positive assortative mating </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mating between like individuals that is more frequent than would be expected on the basis of chance. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> positive control </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Gene regulation in which the binding of a regulatory protein to DNA stimulates transcription (the regulatory protein is an activator). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/positive-selection-94">positive selection</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Selection for an allele that increases fitness. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> positive-strand RNA virus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA virus whose genomic RNA molecule codes directly for viral proteins. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> post-copulatory selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Occurs during and after mating and it refers to selection on traits that influence the likelihood of fertilization and subsequent investment in offspring. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> post-transcriptional regulation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Multiple processes that regulate the efficiency of translation after mRNA is transcribed, including mRNA stability. </div> </div> </div> <div class="wrap"> <strong> postnatal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Anything observed in a baby after birth. </div> </div> </div> <div class="wrap"> <strong> posttranslational modification </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Alteration of a protein after translation; may include cleavage from a larger precursor protein, the removal of amino acids, and the attachment of other molecules to the protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> postzygotic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> After the zygote, usually in reference to mechanisms that prevent continued development of a zygote and thus reproductive isolation. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/prader-willi-syndrome-135">Prader-Willi syndrome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Prader-Willi syndrome (PWS) is a metabolic disorder caused by genetic defects; among its features are short stature, mental retardation, poor muscle tone, and hyperphagia, which leads to childhood obesity. <div class="px10">David B. Allen</div> </div> </div> </div> <div class="wrap"> <strong> praire restoration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An attempt to recreate a prairie climax community within 10 years, when this process naturally takes several hundred years through manipulation of mechanisms of succession to rapidly achieve climax conditions by greatly increasing seed availability, reducing competition by early-successional species, and amending soil to better match late-succession conditions. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> pre-copulatory sexual selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to selection on traits that influence likelihood of mating. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> pre-messenger RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Eukaryotic RNA molecule that is modified after transcription to become mRNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> preadaptation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait that can shift in function to adapt to a changed environment. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> preconception </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The time before a pregnancy has occurred. </div> </div> </div> <div class="wrap"> <strong> predation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Biological interaction where an one organism, the predator, kills and eats another, the prey. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> predation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When one organism kills and consumes another. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> predator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organism that eats consumers. A wolf is a predator that eats rabbits. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> preformationism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Early concept of inheritance proposing that a miniature adult (homunculus) resides in either the egg or the sperm and increases in size during development, with all traits being inherited from the parent that contributes the homunculus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/preimplantation-genetic-diagnosis-pgd-199">preimplantation genetic diagnosis</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Used to select an embryo produced by in vitro fertilization before implantation of the embryo in the uterus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> prenatal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The period between conception and birth. </div> </div> </div> <div class="wrap"> <strong> presymptomatic diagnosis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The identification of a disease before a patient exhibits physical manifestations of the disease. </div> </div> </div> <div class="wrap"> <strong> presymptomatic genetic testing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Testing people to determine whether they have inherited a disease-causing gene before the symptoms of the disease have appeared. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> prevention </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Action taken to avoid getting a disease. </div> </div> </div> <div class="wrap"> <strong> prey </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The organism consumed. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> prezygotic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Before the zygote, usually refers to mechanisms that prevent sperm from reaching eggs and thus maintaining reproductive isolation. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> primary immune response </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Initial clone of cells specific for a particular antigen and generated when the antigen is first encountered by the immune system. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> primary oocyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Oogonium that has entered prophase I. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> primary producers </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that convert energy from light or heat into organic tissue. Plants are an example of a primary producer. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> primary production </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The amount of light energy from the sun converted to chemical energy (organic compounds) by autotrophs (e.g. plants, algae, many bacteria) in an ecosystem within a period of time. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> primary spermatocyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Spermatogonium that has entered prophase I. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> primary structure of a protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The amino acid sequence of a protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> primary succession </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The loss of the entire soil complex due to large, extreme disturbances such as volcanic eruptions or glaciers that Â result in very slow succession due to complete mortality of all living individuals in the system. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/primase-306">primase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Primase is an enzyme that synthesizes short RNA sequences called primers, which serve as starting points for DNA synthesis </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/primer-305">primer</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A primer is a short nucleic acid sequence that provides a starting point for DNA synthesis. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> primordium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The name for a tissue or organ proto-structure in its first stage of development. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/principle-of-independent-assortment-law-of-independent-302">principle of independent assortment</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The principle of independent assortment describes how different genes independently separate from one another during the formation of reproductive cells. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/principle-of-segregation-law-of-segregation-mendel-252">principle of segregation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The principle of segregation describes how pairs of gene variants are separated into reproductive cells. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/principle-of-uniformity-law-of-uniformity-mendel-150">principle of uniformity</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> This principle describes how heterozygotes share a common phenotype. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/principles-of-inheritance-laws-of-inheritance-mendel-143">Principles of Inheritance</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The term that collectively refers to the three principles described by Gregor Mendel that together summarize his extensive experiments studying the patterns of heredity for acquired characteristics. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> prion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Infectious agent that lacks nucleic acid but resembles a virus; believed to replicate by altering the shape of cellular proteins; a likely cause for diseases like scrapie and BSE. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> priority effects </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species arrival in a community prevents the invasion of other species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> probability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Likelihood of a particular event occurring; more formally, the number of times a particular event occurs divided by the number of all possible outcomes. Probability values range from 0 to 1. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> proband </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A person with a trait or disease for whom a pedigree is constructed. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> probe </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A chosen sequence of DNA or RNA that is complementary to a sequence of interest, and used to locate that complementary DNA sequence; alternatively, a measuring instrument. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> processed pseudogene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene that is not expressed or does not code for any protein product and is the result of mature mRNA being subject to retrotransposition into cDNA. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> processing of mRNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process of adding different features to a nascent mRNA strand in eukaryotes, including the addition of a 5' cap, splicing, editing, and polyadenylation. </div> </div> </div> <div class="wrap"> <strong> producers </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms that can produce their own food either by photosynthesis or chemosynthesis. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> productivity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The amount of carbon and energy fixed in photosynthesis by plants and other producers. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> progenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Development where sexual systems mature more quickly than the rest of the body. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> progeny </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Offspring. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/prokaryote-procariote-18">prokaryote</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Prokaryotes are organisms whose cells lack a nucleus and other organelles. This class of organisms includes all of the bacteria </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/prometaphase-281">prometaphase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Prometaphase is the second phase of mitosis, which is a process that separates the duplicated genetic material carried in the nucleus of a parent cell into two, identical daughter cells </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/promoter-259">promoter</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA sequence to which the transcription apparatus binds so as to initiate transcription; indicates the direction of transcription, which of the two DNA strands is to be read as the template, and the starting point of transcription. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> pronucleus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The nucleus in a sperm cell or oocyte prior to fertilization. </div> </div> </div> <div class="wrap"> <strong> proofreading </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Ability of DNA polymerases to remove and replace incorrectly paired nucleotides in the course of replication. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> prophage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phage genome that is integrated into a bacterial chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/prophase-189">prophase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Prophase is the first phase of mitosis, which is a process that separates the duplicated genetic material carried in the nucleus of a parent cell into two, identical daughter cells </div> </div> </div> <div class="wrap"> <strong> prophase I </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of meiosis I. In prophase I, chromosomes condense and pair, crossing over takes place, the nuclear membrane breaks down, and the spindle forms. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> prophase II </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of meiosis after interkinesis. In prophase II, chromosomes condense, the nuclear membrane breaks down, and the spindle forms. Some cells skip this stage. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> proportion of polymorphic loci </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Percentage of loci in which more than one allele is present in a population. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> proteasomal regulation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein stability mediated by the proteasome, a cellular organelle that degrades misfolded proteins that are often tagged with ubiquitin. </div> </div> </div> <div class="wrap"> <strong> proteasome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A structure of multiple proteins that breaks down other proteins tagged by ubiquitin; found in eukaryotes, archaea, and some prokaryotes. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/protein-190">protein</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A connected series of amino acids that may have up to 20 different kinds of side chains; can exist in long fibrous or globular forms; component of macromolecules; forms enzymes and macromolecules active in cellular structure and biochemical processes. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> protein domain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sections of protein sequence (<100 amino acids) that can fold into a specific three-dimensional structure; folding in each domain is typically independent of other domains in the protein. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> protein kinase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzyme that adds phosphate groups to other cellular proteins. </div> </div> </div> <div class="wrap"> <strong> protein kinase A </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A signaling protein that phosphorylates other proteins in response to cAMP signals. </div> </div> </div> <div class="wrap"> <strong> protein kinase B </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A family of protein kinases (Akt1, Akt2 and Akt3) that mediate an array of intracellular signaling cascades. For example, Akt1 is generally thought to mediate cellular survival, and Akt2 is a primary component of insulin signaling. </div> </div> </div> <div class="wrap"> <strong> protein kinase C </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A family of protein kinases that can be divided ubti three subgroups can be identified depending on their mechanism of action.conventional, novel, or atypical. </div> </div> </div> <div class="wrap"> <strong> protein-coding region </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The part of mRNA consisting of the nucleotides that specify the amino acid sequence of a protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> protein-protein association </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When two proteins bind and have an affinity for each other. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/proteome-297">proteome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A proteome is the complete set of proteins expressed by an organism </div> </div> </div> <div class="wrap"> <strong> proto-oncogene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Normal cellular gene that controls cell division. When mutated, it may become an oncogene and contribute to cancer progression. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> provinciality </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The degree of differences among species in different geographic regions. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> provirus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA copy of viral DNA or viral RNA; integrated into the host chromosome and replicated along with the host chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pseudoautosomal region </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small region of the X and Y chromosomes that contains homologous gene sequences. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pseudodominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Expression of a normally recessive allele owing to a deletion on the homologous chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/pseudogene-207">pseudogene</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A nonfunctional member of a gene family that has been derived from a functional gene. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> psi-blast </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A variation of BLAST that uses profiles that are based on sequence multiple-alignments to improve the sensitivity of protein database searches. <div class="px10">Yandell, M. D. and Majoros, W. H. Genomics and natural language processing. Nature Reviews Genetics 3, 601-610 (2002)</div> </div> </div> </div> <div class="wrap"> <strong> pulse labeling </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The addition of a labeled biochemical to cells in order to follow that specific chemical in cells of an organism or in culture. </div> </div> </div> <div class="wrap"> <strong> pulse-chase assay </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An experiment that requires the treatment of cells for a short time with a radioactive biochemical. The radioactive chemical is removed from the cells and the material that was incorporated into the cell is followed over time. </div> </div> </div> <div class="wrap"> <strong> punctuated equilibria / punctuated equilibrium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A pattern of evolutionary change characterized by long periods of little change each followed by a short period of rapid and drastic change. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Punnett square </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Shorthand method of determining the outcome of a genetic cross. On a grid, the gametes of one parent are written along the upper edge and the gametes of the other parent are written along the left-hand edge. Within the cells of the grid, the alleles in the gametes are combined to form the genotypes of the offspring. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pure-breeding </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A line of organisms that breed offspring with an identical phenotype whenever intercrossed. </div> </div> </div> <div class="wrap"> <strong> purifying selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Selection that results in deleterious alleles being removed from the population. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> purine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of nitrogenous base in DNA and RNA. Adenine and guanine are purines. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pyric </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Relating to or resulting from burning. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> pyrimidine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of nitrogenous base in DNA and RNA. Cytosine, thymine, and uracil are pyrimidines <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pyrimidine dimer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Structure in which a bond forms between two adjacent pyrimidine molecules on the same strand of DNA; disrupts normal hydrogen bonding between complementary bases and distorts the normal configuration of the DNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> pyrogeography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The geography of fire, at various scales. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="Q"><div class="padleft10px fleft bold px15">Q</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> q-arm </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The long arm of a chromosome. </div> </div> </div> <div class="wrap"> <strong> Q10 factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The factor by which the reaction increases when you raise temperature by 10 degrees centigrade (or Kelvin). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/qtl-quantitative-trait-locus-quantitative-trait-loci-319">QTL</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Quantitative trait loci; the regions of the genome underlying quantitative traits. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> quantitative characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Continuous characteristic; displays a large number of possible phenotypes, which must be described by a quantitative measurement. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> quantitative genetics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic analysis of complex characteristics or characteristics influenced by multiple genetic factors. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> quantitative trait </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait that varies along a continuum, due to polygenic effects, instead of having discrete states. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> quaternary structure of a protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Interaction of two or more polypeptides to form a functional protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> query sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A genetic sequence used as a probe to search (query) a database. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="R"><div class="padleft10px fleft bold px15">R</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> R plasmid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Plasmid having genes that confer antibiotic resistance to any cell that contains the plasmid. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> R-selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of selection that favors organisms with a high biotic potential and are able to colonize a habitat rapidly, utilizing the food and other resources before other organisms are established and begin to compete. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/radiation-216">radiation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Energy that is transmitted as waves or particles. Some forms of radiation can cause genetic mutations. </div> </div> </div> <div class="wrap"> <strong> radiolabeled leucine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Leucine is an amino acid which can be radiolabelled with tritium. When incorporated into protein by bacteria leucine is assumed to be a measure of bacterial production. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> rain shadow </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An arid region on the leeward side of a mountain range that experiences low levels of precipitation. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> random colonization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of succession where species have only a chance of survival and random colonization by new species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> random genetic drift </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic drift describes random fluctuations in the numbers of gene variants in a population. Genetic drift takes place when the occurrence of variant forms of a gene, called alleles, increases and decreases by chance over time. These variations in the presence of alleles are measured as changes in allele frequencies.Typically, genetic drift occurs in small populations, where infrequently occurring alleles face a greater chance of being lost. Once it begins, genetic drift will continue until the involved allele is either lost by a population or until it is the only allele present in a population at a particular locus. Both possibilities decrease the genetic diversity of a population. Genetic drift is common after population bottlenecks, which are events that drastically decrease the size of a population. In these cases, genetic drift can result in the loss of rare alleles and decrease the gene pool. Genetic drift can cause a new population to be genetically distinct from its original population, which has led to the hypothesis that genetic drift plays a role in the evolution of new species. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> random mating </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When mating is random with respect to the trait in question, the likelihood of a mating between two genotypes is a function of the frequency of the genotypes. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> randomly amplified polymorphic DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic markers made when random sequences are used as primers to amplify DNA. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> rarefaction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Monte Carlo resampling approach to develop a curve to identify and allow comparisons among samples using the minimum sample size of all the collections. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> reaction norms </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pattern of phenotypes that result from genotypes in different environments. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> reading frame </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Particular way in which a nucleotide sequence is read in groups of three nucleotides (codons) in translation. Each reading frame begins with a start codon and ends with a stop codon. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> realized heritability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Heritability measured by response to selection. The ratio of response to one generation of selection to the selection differential of the parents. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> reannealing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In DNA, the process by which two complementary single-stranded DNA molecules pair; also called renaturation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/recessive-271">recessive</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to a trait that is expressed only when genotype is homozygous; a trait that tends to be masked by other inherited traits, yet persists in a population among heterozygous genotypes. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> recessive marker </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Recessive genetic trait. Often included on a compound chromososme to detect rare recombinational events. </div> </div> </div> <div class="wrap"> <strong> reciprocal crosses </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Crosses in which the phenotypes of the male and female parents are reversed. For example, in one cross, a tall male is crossed with a short female and, in the other cross, a short male is crossed with a tall female. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> reciprocal translocation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Reciprocal exchange of segments between two nonhomologous chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> reciprocal transplant experiment </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Experiment designed to demonstrate phenotypic plasticity and genetic differences by raising individuals from different subpopulations in the habitats of all the subpopulations. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> reciprocity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutual or cooperative interchange of favors or privileges between individuals. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> recognition helix </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The helix in a helix-turn-helix motif that interacts with specific nucleotides in the major groove. </div> </div> </div> <div class="wrap"> <strong> recombinant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An adjective describing offspring of a genetic cross, wherein the offspring has a phenotype resembling neither parent, due to recombination events between linked genes during meiosis. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> recombinant congenics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Strains of organisms generated by the inbreeding of the second backcross generation of two separate inbred strains. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/recombinant-dna-164">recombinant DNA</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of DNA sequence that is composed of sequences from two or more different sources or organisms, such as human and pig sources, or synthetic (lab-made) sequences and microorganisms. This customized DNA is typically inserted into a different cell's genome for a specific purpose. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/recombinant-dna-technology-dna-cloning-gene-cloning-7">recombinant DNA technology</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A technology that uses enzymes to cut and paste together DNA sequences of interest. The recombined DNA sequences can be placed into vectors that carry the DNA into a host cell. In this host cell, the customized recombined DNA sequence can be copied or translated. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> recombinant gamete </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Possesses new combinations of genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> recombinant inbred </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A line of genetically identical animals produced by mating successive generations of sibling animals initially descended from the offspring of a cross between two distinct inbred strains. <div class="px10">National Institute of Alcohol Abuse and Alcoholism</div> </div> </div> </div> <div class="wrap"> <strong> recombinant progeny </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Possesses new combinations of traits formed from recombinant gametes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/recombination-226">recombination</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A process by which pieces of DNA are broken and recombined to produce new combinations of alleles. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/recombination-frequency-14">recombination frequency</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A number that describes the proportion of recombinant offspring produced in a genetic cross between two organisms. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> recombination rate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The probability of a crossover event between two loci. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> recruitment </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In evolutionary biology, a synonym for preadaptation where a trait has a shift in function. In population biology, it refers to when juvenile individuals reach sexual maturity and are added to the breeding population. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> recurrence risk </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The chances that an inherited disease will be found in another family member. </div> </div> </div> <div class="wrap"> <strong> recurrent mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Reoccurrence of a certain type of mutation. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> red fluorescent protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutant version of green fluorescent protein that can be used as a reporter construct in live cells. </div> </div> </div> <div class="wrap"> <strong> red queen hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Named for Lewis Carroll.s character who runs continually in order to stay in the same place. States that organisms must continually evolve, or succumb to their predators and parasites that will continue to evolve. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> refuge </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A position or place providing protection or shelter. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> refugia </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Areas where species have survived while becoming extinct in other areas. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> regression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In statistics, the mathematical function that best describes the relationship between two variables, where one is independent and one is dependent. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> regression coefficient </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Statistic that measures how much one variable changes, on average, with a unit change in another variable. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> regulated stability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The biochemical mechanisms responsible for controlling the half-life of a protein or RNA molecule. Often, post-translational or post-transcriptional modifications mediate this regulation. </div> </div> </div> <div class="wrap"> <strong> regulator protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Produced by a regulator gene, a protein that binds to another DNA sequence and controls the transcription of one or more structural genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> regulatory element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA sequence that affects the transcription of other DNA sequences to which it is physically linked. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> regulatory gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA sequence that encodes a protein or RNA molecule that interacts with DNA sequences and affects their transcription or translation or both. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> regulatory promoter </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA sequence located immediately upstream of the core promoter that affects transcription; contains consensus sequences to which transcriptional activator proteins bind. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> reinforcement </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The increase in reproductive isolation due to natural selection for isolation. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/relatedness-123">relatedness</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of genetic similarity. </div> </div> </div> <div class="wrap"> <strong> relative fitness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ratio of the fitness of a genotype to the mean fitness of a population or competing genotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> relaxed state </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Energy state of a DNA molecule when there is no structural strain on the molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> release factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein required for the termination of translation; binds to a ribosome when a stop codon is reached and stimulates the release of the polypeptide chain, the tRNA, and the mRNA from the ribosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> relict </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A population or individual that has survived despite extinction of the rest of the species. Sometimes used as an adjective to describe populations as same. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> renaturation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> See reannealing. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> repetitive DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequences that exist in multiple copies in a genome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replacement substitution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutation where base pairs are replaced with base pairs that code for an alternate amino acid and therefore a different protein product. Also called a nonsynonymous substitution. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/replication-33">replication</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA replication is a process by which a double-stranded DNA molecule is copied into two, identical DNA molecules </div> </div> </div> <div class="wrap"> <strong> replication bubble </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Segment of a DNA molecule that is unwinding and undergoing replication. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replication error </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Replication of an incorporated error in which a change in the DNA sequence has been replicated and all base pairings in the new DNA molecule are correct. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replication fork </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Point at which a double-stranded DNA molecule separates into two single strands that serve as templates for replication. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replication licensing factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that ensures that replication takes place only once at each origin; required at the origin before replication can be initiated and removed after the DNA has been replicated. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replication origin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence of nucleotides where replication is initiated. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replication terminus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Point at which replication stops. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replicative segregation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Random segregation of organelles into progeny cells in cell division. If two or more versions of an organelle are present in the original cell, chance determines the proportion of each type that will segregate into each progeny cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replicative transposition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of transposition in which a copy of the transposable element moves to a new site while the original copy remains at the old site; increases the number of copies of the transposable element. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> replicon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Unit of replication, consisting of DNA from the origin of replication to the point at which replication on either side of the origin ends. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> reporter construct </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene whose expression is easy to observe and is placed upstream to a gene of interest. Observable expression of this upstream gene conveys a report that the downstream sequence has been transcribed. This gene expression can be in the form of color, such as green fluorescent protein or blue beta-galactosidase color in affected cells. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> reporter gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A reporter gene is a DNA sequence that can be attached to a gene under study, which codes for a protein product that can be easily measured </div> </div> </div> <div class="wrap"> <strong> repressible operon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Operon or other system of gene regulation in which transcription is normally on. Something must take place for transcription to be repressed, or turned off. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> repressor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Regulatory protein that binds to a DNA sequence and inhibits transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/reproduction-27">reproduction</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process of making another copy; producing offspring. </div> </div> </div> <div class="wrap"> <strong> reproductive effort </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The amount of resources an organism devotes to reproduction instead of its own growth or maintenance. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> reproductive fitness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The number of offspring an individual produces that survive to reproduce. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> reproductive success </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the number, survival, and future reproduction of offspring produced by individuals. It reflects the genetic contribution of parents to the next generation. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> reproductive variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes the degree of divergence from the mean. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> repulsion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> See trans configuration. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> resolvase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme required for some types of transposition; brings about resolution.which is crossing over between sites located within the transposable element. Resolvase may be encoded by the transposable element or by a cellular enzyme that normally functions in homologous recombination. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> resource holding potential </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fighting ability (i.e., the ability to defend territories or engage with opponents directly). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> resource ratio hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A proposal by David Tilman (1985) which models successional shifts in plant communities based on the assumption that succession is driven by a tradeoff in competition for nutrients in early succession, and for light in late succession. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> resource ratio theory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Competitive interactions are based on species. resource consumption and resource supply rates; coexistence occurs when species exhibit trade-offs in their ability to utilize different resources. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> respiration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In metabolism, a biochemical process inside cells that breaks down organic material and releases energy; occurs in mitochondria and generates ATP, CO2 and H20. In gas exchange, the transfer of oxygen and carbon dioxide in opposite directions across a membrane to regulate oxygen availability inside an organism. <div class="px10">© Nature Education.</div> </div> </div> </div> <div class="wrap"> <strong> response element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Common DNA sequence found upstream of some groups of eukaryotic genes. A regulatory protein binds to a response element and stimulates the transcription of a gene. The presence of the same response element in several promoters or enhancers allows a single factor to simultaneously stimulate the transcription of several genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> response to selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Change in phenotype in one generation as a result of selection. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> restoration ecology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The scientific study of repairing disturbed ecosystems through human intervention; an attempt to speed successional processes to reach a desired climax community. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/restriction-endonuclease-restriction-enzyme-restriction-enzymes-144">restriction endonuclease</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Technical term for a restriction enzyme, which recognizes particular base sequences in DNA and makes double-stranded cuts nearby. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> restriction enzyme </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme that recognizes particular base sequences in DNA and makes double-stranded cuts nearby; also called restriction endonuclease. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> restriction fragment length polymorphism (RFLP) </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Variation in the pattern of fragments produced when DNA molecules are cut with the same restriction enzyme; represents a heritable difference in DNA sequences and can be used in gene mapping. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/restriction-mapping-283">restriction mapping</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Restriction mapping is a method used to map an unknown segment of DNA by breaking it into pieces and then identifying the locations of the break points </div> </div> </div> <div class="wrap"> <strong> restriction site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The DNA sequence cut by a restriction enzyme. Each restriction enzyme has a particular DNA sequence it recognizes and restricts. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> reticulate evolution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Hybridization of related taxa. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/retrotransposon-213">retrotransposon</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of transposable element in eukaryotic cells that possesses some characteristics of retroviruses and transposes through an RNA intermediate. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> retrovirus </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA virus capable of integrating its genetic material into the genome of its host. The virus injects its RNA genome into the host cell, where reverse transcription produces a complementary, double-stranded DNA molecule from the RNA template. The DNA copy then integrates into the host chromosome to form a provirus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> revegetation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The establishment of vegetation on sites where it has been previously lost, often with erosion control as the primary goal. For example, vegetated buffers are strips of vegetation that protect water quality. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> reverse chromosome duplication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Duplication of a chromosome segment in which the sequence of the duplicated segment is inverted relative to the sequence of the original segment. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> reverse mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mutation that changes a mutant phenotype back into the wild type. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> reverse transcriptase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme capable of synthesizing complementary DNA from an RNA template. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> reverse transcriptase PCR </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A polymerase chain reaction that produces multiple copies of a selected RNA sequence rather than a DNA sequence; compare to polymerase chain reaction. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> reverse transcription </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Synthesis of DNA from an RNA template. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> reversed sexual dimorphism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Females evolve more elaborate secondary sexual characters than males. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/rflp-285">RFLP</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Restriction fragment length polymorphisms, or RFLPs, are differences among individuals in the lengths of DNA fragments cut by enzymes. </div> </div> </div> <div class="wrap"> <strong> rhizomes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An underground characteristically horizontal stem of a plant growing near the soil surface. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> rho factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Subunit of bacterial RNA polymerase that facilitates termination of transcription of some genes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> rho-dependent terminator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence in bacterial DNA that requires the presence of the rho subunit of RNA polymerase to terminate transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> rho-independent terminator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence in bacterial DNA that does not require the presence of the rho subunit of RNA polymerase to terminate transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> ribonuclear protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proteins that interact in the nucleus with RNA, often to help catalyze splicing reactions. </div> </div> </div> <div class="wrap"> <strong> ribonucleic acid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA; A single-stranded polymer of nucleotides that contain the sugar ribose; made through the process of transcription; three primary types exist, and all three function in the interpretation of the information stored in DNA. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ribonucleoside triphosphate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Substrate of RNA synthesis; consists of a ribose sugar, a nitrogenous base, and three phosphates linked to the 5'-carbon atom of the sugar. In transcription, two of the phosphates are cleaved, producing an RNA nucleotide. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> ribonucleotide </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Nucleotide containing a ribose sugar; present in RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> ribose sugar </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Five-carbon sugar in RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> ribosomal RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA that is a component of the ribosome. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/ribosome-194">ribosome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A complex molecule made of ribosomal RNA molecules and proteins that form a factory for protein synthesis in cells. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> ribosomes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cellular organelles that are the sites for translation of mRNA into protein. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> riboswitch </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Regulatory sequences in an RNA molecule. When an inducer molecule binds to the riboswitch, it changes the configuration of the RNA molecule and alters the expression of the RNA, usually by affecting termination of transcription or affecting translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/ribozyme-140">ribozyme</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA molecule that can act as a biological catalyst. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> riffle habitate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A stream location with change in height of the stream bottom. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> ring-X chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Highly unstable X chromosomes in which both ends have deletions and the ends fuse to form a ring. </div> </div> </div> <div class="wrap"> <strong> riparian ecosystems </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Organisms and the physical environment found in narrow strips of land that border creeks, rivers or other bodies of water. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> risk </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The possibility of loss or a negative outcome; can be theoretical or measured epidemiologically. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> RNA cleavage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Breaking of an RNA strand into smaller pieces, usually by a nucleolytic enzyme such as a ribozyme. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> RNA editing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process in which the protein-encoding sequence of an mRNA is altered after transcription. The amino acids specified by the altered mRNA are different from those predicted from the nucleotide sequence of the gene encoding the protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> RNA interference </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process in which cleavage of double-stranded RNA produces small interfering RNAs (siRNAs) that bind to mRNAs containing complementary sequences and bring about their cleavage and degradation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/rna-polymerase-106">RNA polymerase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme that synthesizes RNA from a DNA template during transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> RNA polymerase I </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Eukaryotic RNA polymerase that transcribes large ribosomal RNA molecules (18 S rRNA and 28 S rRNA). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> RNA polymerase II </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Eukaryotic RNA polymerase that transcribes pre-messenger RNA and some small nuclear RNAs. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> RNA polymerase III </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Eukaryotic RNA polymerase that transcribes transfer RNA, small ribosomal RNAs (5 S rRNA), and some small nuclear RNAs. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> RNA processing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In eukaryotic cells, the process of removing introns and modifying the ends of the precursor RNA transcript prior to leaving the nucleus. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> RNA replication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process in some viruses by which RNA is synthesized from an RNA template. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> RNA silencing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mechanism by which double-stranded RNA is cleaved and processed to yield small single-stranded interfering RNAs (siRNAs), which bind to complementary sequences in mRNA and bring about the cleavage and degradation of mRNA; also known as RNA interference and posttranscriptional RNA gene silencing. Some siRNAs also bind to complementary sequences in DNA and guide enzymes to methylate the DNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> RNA splicing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process by which introns are removed and exons are joined together. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> RNA-coding region </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence of DNA nucleotides that encodes an RNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Robertsonian translocation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Translocation in which the long arms of two acrocentric chromosomes become joined to a common centromere, resulting in a chromosome with two long arms and usually another chromosome with two short arms. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> rolling-circle replication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Replication of circular DNA that is initiated by a break in one of the nucleotide strands, producing a double-stranded circular DNA molecule and a single-stranded linear DNA molecule, the latter of which may circularize and serve as a template for the synthesis of a complementary strand. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> rooted tree </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phylogenetic tree in which one internal node represents the common ancestor to all other organisms (nodes) on the tree. In a rooted tree, all the organisms depicted have a common ancestor. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> rubric </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A set of expectations or ideal characteristics against which a work is measured; can be used in grading or in the creation of new material that follows set standards. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="S"><div class="padleft10px fleft bold px15">S</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/s-phase-synthesis-phase-s-phase-24">S phase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of interphase in the cell cycle. In S phase, DNA replicates. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> saltation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutation or sudden change in a lineage. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sample </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Subset used to describe a population. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/sampling-error-231">sampling error</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Deviations from expected ratios due to chance occurrences when the number of events is small. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> SAT B1 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A human homeodomain-containing transcription factor. </div> </div> </div> <div class="wrap"> <strong> satellite RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of viral RNA, often found associated with plant viruses, that has self-splicing (catalytic) properties. </div> </div> </div> <div class="wrap"> <strong> scala naturae </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A Latin term, translated as the "ladder of nature." An obsolete concept that life was organized in a linear hierarchy, with organisms increasing in perfection from lower forms to higher forms. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> scale </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> To expand in scope, usually exponentially (verb); the spatial relationship of objects or organisms, as the relate to each other or their environment (noun). <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> scatter caching </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When an animal stores food in various spots for future consumption. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> sclerophyllous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Hard, leathery, thick, and usually evergreen leaves. The word comes from the Greek sclero (hard) and phyllon (leaf). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> search space </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> </div> </div> </div> <div class="wrap"> <strong> second filial cross </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Interbreeding of second generation individuals generated from a cross between two parents. </div> </div> </div> <div class="wrap"> <strong> second polar body </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the products of meiosis II in oogenesis; contains a set of chromosomes but little of the cytoplasm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> secondary immune response </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Clone of cells generated when a memory cell encounters an antigen; provides long-lasting immunity. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> secondary oocyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the products of meiosis I in female animals; receives most of the cytoplasm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> secondary production </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The formation of living mass of a heterotrophic population or group of populations over some period of time; may refer to animals or other heterotrophs such as fungi and bacteria. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> secondary production applications </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Methods that include energy flow analyses as well as other applications, such as describing temporal patterns of niche partitioning and quantifying food web linkages. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> secondary spermatocyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Product of meiosis I in male animals. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> secondary structure of a protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Regular folding arrangement of amino acids in a protein. Common secondary structures found in proteins include the alpha helix and the beta pleated sheet. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> secondary succession </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species survive in the soil during large, low intensity disturbances, such as plowing in conventional agriculture, and can quickly recolonize areas after the disturbance. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> securin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Molecule that normally binds the enzyme separase, preventing it from cleaving cohesin molecules that hold the sister chromatids together. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> segment-polarity genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Set of segmentation genes in fruit flies that affect the organization of segments. Mutations in these genes cause part of each segment to be deleted and replaced by a mirror image of part or all of an adjacent segment. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/segmentation-genes-177">segmentation genes</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Set of about 25 genes in fruit flies that control the differentiation of the embryo into individual segments, affecting the number and organization of the segments. Mutations in these genes usually disrupt whole sets of segments. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> segregating </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A population with more than one common allele and thus more than one common phenotype for a given trait. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> segregating generation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Generation in which there is more than one expected genotype. </div> </div> </div> <div class="wrap"> <strong> segregating inbred lines </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Line developed by inbreeding but in which one or more loci remain heterozygous. This generally requires progeny screening each generation and selection of heterozygous parents. </div> </div> </div> <div class="wrap"> <strong> segregation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any process of separating one set of things from another; in biology, the separation of alleles into different gametes during meiosis. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> segregation distortion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When gene alleles in a heterozygote do not segregate in a 1:1 ratio among gametes; instead, one allele appears in more than 50% of the gametes. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/selection-61">selection</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Nonrandom differential survival or reproduction of classes of phenotypically different entities. See also natural selection, artificial selection. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> selection coefficient </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of the relative fitness of a genotype. A number between 0 and 1 where 1 means the genotype has been entirely selected against and thus makes no contribution to the next generation. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selection differential </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The difference between the mean of the parents and the mean of the entire population for a quantitative trait under selection pressure. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selection gradient </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A descriptive statistic; used to measure the intensity with which traits are influenced by direct selection. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selection plateau </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Also called selection limit. The point where a population is homozygous for the preferred alleles and will no longer respond to selection.; <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selective advantage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The increase in fitness due to an allele or trait. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selective agent </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An environmental condition or process that exerts selection pressure. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selective breeding </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The controlled breeding of specific plants or animals to produce offspring with desirable traits; may involve mutliple generations to achieve results. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selective pressure </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Biotic or abiotic factors, such as limits on resources (food, habitat, mates) and threats (predators, disease), that impact reproductive success. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> selective sweep </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When a favorable mutation is strongly selected for and increases in frequency, the corresponding rise in frequency of alleles positioned nearby. Also called "genetic hitchhiking." <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> self-form </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The idea that an ecosystem could form a stable climax community. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> self-incompatibility </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Plants that are unable to self-fertilize. This promotes outcrossing and the resulting increase in genetic variation. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> self-renew </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The idea that an ecosystem could form a stable climax community after a disturbance. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> self-renewal </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A stem cell's ability to divide and produce a daughter cell capable of the same. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selfing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Self-fertilization; a cross where the same organism provides both gametes. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> selfish DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any sequence of DNA that is able to replicate itself and does not confer any advantage to the organism. It may be deleterious. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> semelparity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Life histories characterized by death after first reproduction. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> semelparous </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> From the roots "to beget once," a reproductive strategy characterized by only one reproductive event. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> semiconservative replication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Replication in which the two nucleotide strands of DNA separate, each serving as a template for the synthesis of a new strand. All DNA replication is semiconservative. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> semidominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The lack of dominance of any specific allele at a locus. Heterozygotes have a phenotype intermediate between the two parents. </div> </div> </div> <div class="wrap"> <strong> semispecies </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A group of populations that have reduced gene flow between them yet are not completely reproductively isolated. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sense codon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Codon that specifies an amino acid in a protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> separase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Molecule that cleaves cohesin molecules, which hold the sister chromatids together. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/sequence-alignment-218">sequence alignment</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Regions of local similarity of DNA, RNA, or amino acid sequences. </div> </div> </div> <div class="wrap"> <strong> sequential assessment model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A model that assumes that each individual gathers information about the resource holding potential (RHP) of their opponent, compare this to their own RHP, and give up when they know they are weaker. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> sequential hermaphroditism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Phenomenon in which the sex of an individual organism changes in the course of its lifetime; the organism is male at one age or developmental stage and female at a different age or stage. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sere </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The stages in a successional sequence. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> serial homology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When repeated related structures, such as vertebrae, have similarities in development, function and/or ancestral form. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> serotiny </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An ecological adaptation exhibited by some seed plants, in which seed release occurs in response to an environmental trigger. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> serotonin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A monoamine neurotransmitter that can act directly on neurons to modulate their activity via ionic or G-protein coupled receptors; chemical name 5-hydroxytryptamine, or 5-HT. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> serpentine soils </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Soils containing large amounts of Fe and Mg, relatively small amounts of Si and Ca, and sometimes large amounts of other metals (Ni, Co, Cu, Zn, etc.) and are often more shallow and stony than other soils. As a result, serpentine soils can be challenging substrates for plant growth. There are a number of cases in which populations have adapted to serpentine soil conditions, sometimes resulting in speciation. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> sex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The biological or physiological characteristics that determine whether an organism is male or female or other; the physical act between organisms involving sex organs. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/sex-chromosomes-sex-chromosome-108">sex chromosomes</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromosomes that differ morphologically or in number in males and females. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/sex-determination-99">sex determination</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Specification of sex (male or female). Sex-determining mechanisms include chromosomal, genic, and environmental sex-determining systems. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sex ratio </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The number of males compared to the number of females in a population. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sex-determining region Y gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> On the Y chromosome, a gene that triggers male development; also known as the testis-determining factor (TDF) gene. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sex-influenced characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Encoded by autosomal genes that are more readily expressed in one sex. For example, an autosomal dominant gene may have higher penetrance in males than in females or an autosomal gene may be dominant in males but recessive in females. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sex-limited characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Encoded by autosomal genes and expressed in only one sex. Both males and females carry genes for sex-limited characteristics, but the characteristics appear in only one of the sexes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sex-linked </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait governed by a genetic locus found on a sex chromosome; males and females do not have the same probability of expressing such a trait. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> sex-linked characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Characteristic determined by a gene or genes on sex chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sex-linked dominant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An allele on the X chromosome that encodes a trait that is inherited by one-half of the offspring from an affected mother; an affected father would pass the trait to all of his daughters and none of his sons. </div> </div> </div> <div class="wrap"> <strong> sex-linked recessive </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait encoded by a gene found on a sex chromosome that requires two copies of the allele to be manifested in the organism. If a sex-linked trait is the result of a recessive allele on the X chromosome, most daughters will not be affected. However, if a male offspring receives a mutant allele from the mother's genetic contribution, he will be affected because he is hemizygous for X-chromosome genes. </div> </div> </div> <div class="wrap"> <strong> sexual conflict </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Both sexes seek to optimize their reproductive success, but their genetic interests are not aligned. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/sexual-reproduction-255">sexual reproduction</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Production of offspring whose genetic constitution is a mixture of those of two potentially genetically different gametes. <div class="px10"> © 2005 by Sinauer Associates, Inc. All rights reserved. Futuyma, D. Evolution.</div> </div> </div> </div> <div class="wrap"> <strong> sexual selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In a population, the force that drives the proliferation of phenotypes that confer a mating advantage. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sexually selected traits </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Traits that increase the individual's reproductive success, even at the expense of their survival. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> Shannon's INDEX </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Proposed that the number of species on any island reflects a balance between the rate at which new species colonize it and the rate at which populations of established species become extinct An index used to describe species diversity. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/shifting-balance-theory-117">shifting balance theory</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A largely verbal theory of evolution which maintains that the interaction among natural selection, genetic drift, and migration is more important that the action of any single force. Sewall Wright argued that this theory helped to explain how species could effectively search for the global (and not merely local) optimum. </div> </div> </div> <div class="wrap"> <strong> Shine-Dalgarno sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consensus sequence found in the bacterial 5' untranslated region of mRNA; contains the ribosome-binding site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> short interspersed element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Short DNA sequence repeated many times and interspersed throughout the genome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> short tandem repeats </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A repeat of a short sequence of DNA where the number of repeats can vary between individuals and be used as molecular markers. Also called simple sequence repeat polymorphisms, simple sequence repeats, microsatellites. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> shuttle vector </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cloning vector that allows DNA to be transferred to more than one type of host cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sibling species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Species that are difficult to distinguish based on morphological characteristics. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sigma factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Subunit of bacterial RNA polymerase that allows the RNA polymerase to recognize a promoter and initiate transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sign of disease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A physical symptom that is indicative of a disease. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> signal sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> From 15 to 30 amino acids that are found at the amino end of some eukaryotic proteins and direct the protein to specific locations in the cell; usually cleaved from the protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> signal transduction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The transfer of extracellular signal to an intracellular process by a series of reactions between membrane-bound and intracellular proteins and other molecules. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> silencing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> General term for epigenetic negative control of gene expression. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/silent-mutation-10">silent mutation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutation where a change in a DNA codon does not result in a change in amino acid translation. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> silent substitution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutation where a change in a DNA codon does not result in a change in amino acid translation. The resulting protein product will also be unchanged. Also called a synonymous substitution. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Simian Virus 40 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A DNA polyomavirus that has been linked to cancer. </div> </div> </div> <div class="wrap"> <strong> simple sequence repeat polymorphisms </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A repeat of a short sequence of DNA where the number of repeats can vary between individuals and be used as molecular markers. Also called short tandem repeats, simple sequence repeats, microsatellites. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> simple sequence repeats </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A repeat of a short sequence of DNA where the number of repeats can vary between individuals and be used as molecular markers. Also called short tandem repeats, simple sequence repeats, microsatellites. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> simulation model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Analysis of variables via a computer model to predict outcomes. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/single-nucleotide-polymorphism-snp-148">single nucleotide polymorphism</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A single nucleotide polymorphism, or SNP, is a single base-pair difference in the DNA sequence of individual members of a species; not necessarily a pathological mutation, but commonly studied as a covarying marker of complex disease phenotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> single-strand binding protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Binds to single-stranded DNA in replication and prevents it from annealing with a complementary strand and forming secondary structures. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sire </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The male parent of a domesticated animal, such as those bred for commercial purposes. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sister chromatids </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Two copies of a chromosome that are held together at the centromere. Each chromatid consists of a single DNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sister taxa </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Two groups descended from an immediate common ancestor that are more closely related to each other than to other groups. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> site-directed mutagenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Produces specific nucleotide changes at selected sites in a DNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> slave-makers </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A type of social parasitism in ants where colonies raid other ant colonies for the brood that then later eclose into workers (i.e., slaves) that are imprinted on the host colony and perform for their masters various tasks. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> small cytoplasmic RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small RNA molecule found in the cytoplasm of eukaryotic cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> small interfering RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Single-stranded RNA molecule (usually from 21 to 25 nucleotides in length) produced by the cleavage and processing of double-stranded RNA; binds to complementary sequences in mRNA and brings about the cleavage and degradation of the mRNA. Some siRNAs bind to complementary sequences in DNA and bring about their methylation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> small nuclear ribonucleoprotein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Structure found in the nuclei of eukaryotic cells that consists of snRNA and protein; functions in the processing of pre-mRNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> small nuclear RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small RNA molecule found in the nuclei of eukaryotic cells; functions in the processing of pre-mRNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> small nucleolar RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small RNA molecule found in the nuclei of eukaryotic cells; functions in the processing of rRNA and in the assembly of ribosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> small ribosomal subunit </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The smaller of the two subunits of a functional ribosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/snp-295">SNP</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A single nucleotide polymorphism, or SNP, is a single base-pair difference in the DNA sequence of individual members of a species; not necessarily a pathological mutation, but commonly studied as a covarying marker of complex disease phenotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> social behavior </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The set of interactions among individuals in the same species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> social cognition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ability of an animal to forecast how its own actions will affect its future relationships within a social group. Exists in chimpanzees (although it is more limited than in humans) and may extend to other species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> social groups </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stable groups of repeatedly interacting individuals. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> solar radiation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The visible and near-visible (ultraviolet and near-infrared) radiation emitted from the sun. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> somatic cell </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any cell in an organism that is not a sex cell, not a gamete. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> somatic cell nuclear transfer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cell culture process that yields embryonic stem (ES) cells; involves the transfer of a somatic cell nucleus to an enucleated egg, and growth to the blastocyst stage to yield multiple copies. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> somatic gene therapy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A therapy that treats somatic cells in a body, altering genee expression to improve cell or tissue health. The genetic alteration does not transfer to offpsring. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> somatic hypermutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> High rate of somatic mutation such as that in genes encoding antibodies. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> somatic mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mutation in a cell that does not give rise to a gamete. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> somatic production </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The production of cells/tissues other than for reproduction (gametes). <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> somatic recombination </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Recombination in somatic cells, such as maturing lymphocytes, among segments of genes that encode antibodies and T-cell receptors. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> somatic-cell hybridization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Fusion of different cell types. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> SOS system </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> System of proteins and enzymes that allow a cell to replicate its DNA in the presence of a distortion in DNA structure; makes numerous mistakes in replication and increases the rate of mutation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/southern-blot-289">Southern blot</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A Southern blot is a laboratory method used to detect specific DNA molecules from a mixture of DNA molecules </div> </div> </div> <div class="wrap"> <strong> Southern blotting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method to identify segments of DNA that have a specific sequence. Briefly, DNA is digested with a specific enzyme and the fragments are separated by gel electrophoresis. The DNA fragments are transferred to a membrane that is probed with a labeled piece of DNA complementary to the DNA sequence of interest. </div> </div> </div> <div class="wrap"> <strong> Sp1 transcription factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A transcription factor involved in different aspects of development. Sp1 has a zinc finger domain that mediates DNA binding. </div> </div> </div> <div class="wrap"> <strong> spatial comparison </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Comparing similar communities that occur in different locations. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> spatial structure </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The arrangement of individuals in a population in an area. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> specialist predators </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Predators that feed exclusively on a prey species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> specialized transduction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transduction in which genes near special sites on the bacterial chromosome are transferred from one bacterium to another; requires lysogenic bacteriophages. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/speciation-183">speciation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Speciation is the evolutionary process by which a new species comes into being </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/species-312">species</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A biological species is a group of organisms that can reproduce with one another in nature and produce fertile offspring </div> </div> </div> <div class="wrap"> <strong> species coexistence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The long term co-occurrence of species in the same general location. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> species composition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The species present in a community. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> species diversity </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of the number of species in a community, and a measure of the abundance of each species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> species evenness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A description of the distribution of abundance across the species in a community. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> species richness </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The number of species in a community. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> species selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A concept of selection at the species level which proposes that the rates of speciation and extinction are due to differences in characteristics within species. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> species-area curves </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The result of plotting the species richness of a particular sample against that area of that sample which reveals that as the size of a natural area increases, the number of species in that area increases as well. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> spectral karyotyping </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A molecular cytogenetic technique that allows the visualization of all the chromosomes at once using different colored markers for each chromosome. </div> </div> </div> <div class="wrap"> <strong> speed congenics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A variation on regular congenics. At generation N(2), individual mice (generally males) are genotyped for 60 to 100 microsatellite markersb and the mice with the greatest share of the inbred background chromosomes of interest in are selected as parents. (Males are used because a single male can be backcrossed to many different parental strain females). This process may eventually be further accelerated by microarray screens. The savings can be considerable. Speed congenic technology might produce a congenic strain in 12 to 18 months versus two to three years. </div> </div> </div> <div class="wrap"> <strong> sperm competition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Post-copulatory male-male competition that happens when females mate with multiple males and their ejaculates compete inside the female reproductive tract for access to eggs. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> spermatid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Immediate product of meiosis II in spermatogenesis; matures to sperm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> spermatogenesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sperm production in animals. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> spermatogonium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Diploid cell in the testis; capable of undergoing meiosis to produce a sperm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> spindle </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A subcellular structure composed of microtubules that separates chromosomes in a cell during cell division. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/spindle-fibers-304">spindle fibers</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Spindle fibers are protein structures that pull apart the genetic material in a cell when the cell divides </div> </div> </div> <div class="wrap"> <strong> spindle microtubule </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Microtubule that moves chromosomes in mitosis and meiosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> spindle pole </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Point from which spindle microtubules radiate. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> spliced recombinants </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Possible outcome of homologous recombination, consisting of two heteroduplex DNA molecules, with the DNA at each end in combinations different from those originally present. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> spliceosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Large complex consisting of several RNAs and many proteins that splices protein-encoding pre-mRNA; contains five small ribonucleoprotein particles (U1, U2, U4, U5, and U6). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/splicing-138">splicing</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Removal of introns and connecting of exons in eukaryotic pre-mRNAs. <div class="px10"> © 2008 by Sinauer Associates, Inc. All rights reserved. Sadava, D. Life: the science of biology. 8th Edition.</div> </div> </div> </div> <div class="wrap"> <strong> spontaneous mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Arises spontaneously from natural changes in DNA structure or from errors in replication. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> sporophyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Diploid phase of the life cycle in plants. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> SR proteins </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Group of serine- and arginine-rich proteins that regulate alternative splicing of pre-mRNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> stability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ability to resist change or to return to a condition after a change in condition. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> stabilizing selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Selection that decreases genetic diversity and stabilizes the mean of a trait in population around a particular, usually optimal, value. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> stable equilibrium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A perturbed system returns to the same equilibrium state. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> standard deviation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of the range of the data. The mean of all the means of all the sets of data. The square root of the variance. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> stasis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A characteristic of a time period during which few or no changes take place; in evolution, the overall absence of evolutionary change in one or more characters for some period of evolutionary time. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> static allometry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The relationship of x and y that are traits measured in different individuals at the same developmental stage within a population or species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/statistical-linkage-251">statistical linkage</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The estimate that two genes are located on a chromosome together such that they are likely to be inherited together. </div> </div> </div> <div class="wrap"> <strong> statistically significant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Likely due to causes other than chance. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> statistics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mathematical science related to the examination of data and its relevance. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/stem-cells-42">stem cells</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In animals, undifferentiated cells that are capable of extensive proliferation. A stem cell generates more stem cells and a large clone of differentiated progeny cells. <div class="px10"> © 2008 by Sinauer Associates, Inc. All rights reserved. Sadava, D. Life: the science of biology. 8th Edition.</div> </div> </div> </div> <div class="wrap"> <strong> stepping stones </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Small unconnected patches of habitat that are close enough together to allow movement across the landscape. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> steric interference </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Interrupts a biochemical process by physically preventing the process from occurring. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> stochastic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Having a random probability distribution; hard to predict. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> stop codon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Codon in mRNA that signals the end of translation; also called nonsense codon or termination codon. There are three common stop codons: UAA, UAG, and UGA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> strain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An artificial line of a species; usually not pure-breeding. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> strand slippage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Slipping of the template and newly synthesized strands in replication in which one of the strands loops out from the other and nucleotides are inserted or deleted on the newly synthesized strand. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> strata </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Layers of material; used to describe sedimentary rock in geology, tissues in biology, and ranges of vegetation in ecology. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> stratosphere </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The second layer of Earth's atmosphere, above the troposphere and below the mesosphere. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> structural gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA sequence that encodes a protein that functions in metabolism or biosynthesis or that plays a structural role in the cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> structural genomics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Area of genomics that studies the organization and sequence of information contained within genomes; sometimes used by protein chemists to refer to the determination of the three-dimensional structure of proteins. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> subfunctionalization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Evolution of redundant genes where each one retains some of the functionality of the original gene. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> subjective resource value </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> How much each opponent values the resource. A given resource may have absolute value (e.g., the size of a territory or the number of calories in a food item) but each opponent may place a different subjective value on it (e.g., a hungry individual may value a food item more highly than an individual that has just eaten). Differences in RV can lead to differences in willingness to fight. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> submetacentric chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromosome in which the centromere is displaced toward one end, producing a short arm and a long arm. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> subpopulation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A small localized interbreeding group within a larger population. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> subspecies </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A subset of a species. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> substrain </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Two inbred lines from a common origin may be considered substrains. This implies that the substrains differ at several loci. </div> </div> </div> <div class="wrap"> <strong> succession of species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The predictable and natural series of changes that occur to assemblages of species in an ecosystem. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sucker shoot </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An informal term for basal shoots arising from the meristem of a plant, near the base or below ground level, either from a rhizome or root. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sum of squares </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An unadjusted measure of variability; for a sample group it is the sum of squared deviations from the mean and the numerator of the variance. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/supercoiling-positive-supercoiling-negative-supercoiling-supercoiled-264">supercoiling</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Coiled tertiary structure that forms when strain is placed on a DNA helix by overwinding or underwinding of the helix. An overwound DNA exhibits positive supercoiling; an underwound DNA exhibits negative supercoiling. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> superspecies </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The major subdivision of a genus or subgenus. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> suppressor mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Hides or suppresses the effect of another mutation at a site that is distinct from the site of the original mutation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> surface plasmon resonance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The collective oscillation of electrons that occurs when surface plasmon waves are excited by light deflection at a metal-liquid interface; used to investigate protein-protein interactions, such as antibody-antigen interactions, and can serve as a biosensor;abbrevitaed as SPR. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> surrogate </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An individual that substitutes for another, by appointment, choice, or default. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> swidden </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The generic anthroplogical term for all varieties of slash-and-burn cultivation. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> symbiosis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Literally "living together," a close association between two or more species. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sympatric </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Literally "same fatherland" and used to describe populations in the same or overlapping area. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> sympatric speciation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An evolutionary process which forms new species from an ancestral species in the same geographic location. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> sympatry </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The occurrence of species together in the same area. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/symptom-22">symptom</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Physical manifestation of disease. </div> </div> </div> <div class="wrap"> <strong> synapomorphy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A shared derived trait evolved in a common ancestor. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> synapsis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Close pairing of homologous chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> synaptonemal complex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Three-part structure that develops between synapsed homologous chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> syndrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A set of symptoms that are exhibited together that are indicative of a specific disease. </div> </div> </div> <div class="wrap"> <strong> synergy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When effects of two factors (such as toxicity of two chemicals) combine so that their effect together is significantly greater than the sum of the effects of each factor by itself. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> synonymous codons </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Different codons that specify the same amino acid. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> synonymous substitution </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutation where a change in a DNA codon does not result in a change in amino acid translation. The resulting protein product will also be unchanged. Also called a silent substitution. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> syntenic genes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Determined to be on the same chromosome by physical-mapping techniques. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/synteny-137">synteny</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A term used to describe the state of two or more genes being present on the same chromosome, though not necessarily linked. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="T"><div class="padleft10px fleft bold px15">T</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> T-cell receptor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Found on the surface of a T cell, a receptor that simultaneously binds a foreign and a self-antigen on the surface of a cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> T-lymphocyte </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A white blood cell of the immune system that has molecules on its surface that recognize specific antigens. </div> </div> </div> <div class="wrap"> <strong> tandem chromosome duplication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Duplication of a chromosome segment that is adjacent to the original segment. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tandem repeat sequences </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA sequences repeated one after another; tend to be clustered at specific locations on a chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Taq polymerase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> DNA polymerase commonly used in PCR reactions. Isolated from the bacterium Thermus aquaticus, the enzyme is stable at high temperatures, and so it is not denatured during the strand-separation step of the cycle. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> target gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene of interest. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> targets of selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The phenotype characters under direct selection. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/tata-box-313">TATA box</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A TATA box is a DNA sequence that indicates the point at which a genetic sequence can be read and decoded </div> </div> </div> <div class="wrap"> <strong> TATA-binding protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Polypeptide chain found in several different transcription factors that recognizes and binds to sequences in eukaryotic promoters. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> taxon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A taxonomic category. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> taxonomy category </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any rank of classification, such as a genus or family, in a taxonomy. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> TBP-associated factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that combines with the TATA-binding protein to form a transcription factor. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> teleology </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The belief that purpose and design are part of nature. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> telocentric chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chromosome in which the centromere is at or very near one end. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> telomerase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme that is made up of both protein and RNA and replicates the ends (telomeres) of eukaryotic chromosomes. The RNA part of the enzyme has a template that is complementary to repeated sequences in the telomere and pairs with them, providing a template for the synthesis of additional copies of the repeats. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/telomere-225">telomere</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stable end of a chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> telomere-associated sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence found at the end of a chromosome next to the telomeric sequence; consists of relatively long, complex, repeated sequences. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> telomeric sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence found at the ends of a chromosome; consists of many copies of short, simple sequences repeated one after the other. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/telophase-128">telophase</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Telophase is the fifth and final phase of mitosis, which is a process that separates the duplicated genetic material carried in the nucleus of a parent cell into two, identical daughter cells. </div> </div> </div> <div class="wrap"> <strong> telophase I </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of meiosis I. In telophase I, chromosomes arrive at the spindle poles. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> telophase II </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Stage of meiosis II. In telophase II, chromosomes arrive at the spindle poles. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> temperate phage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacteriophage that utilizes the lysogenic cycle, in which the phage DNA integrates into the bacterial chromosome and remains in an inactive state. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> temperature-sensitive allele </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Expressed only at certain temperatures. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> template strand </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The strand of DNA that is used as a template during transcription. The RNA synthesized during transcription is complementary and antiparallel to the template strand. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/teratogen-103">teratogen</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Anything, physical or chemical, that can deform or harm a developing embryo. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> terminal inverted repeats </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequences found at both ends of a transposable element that are inverted complements of one another. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> termination codon </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Codon in mRNA that signals the end of translation; also called nonsense codon or stop codon. There are three common termination codons: UAA, UAG, and UGA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> terminator </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence of DNA nucleotides that causes the termination of transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> territory </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An area of land designated for a specific purpose; an portion of habitat defended by an organism or a group of organisms against others. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> tertiary structure of a protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Higher-order folding of amino acids in a protein to form the overall three-dimensional shape of the molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/test-cross-169">test cross</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cross between an individual with an unknown genotype and an individual with the homozygous recessive genotype. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> testis-determining factor gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> On the Y chromosome, a gene that triggers male development; also known as the sex determining region Y (SRY) gene. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tetrad </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The four products of meiosis; all four chromatids of a homologous pair of chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tetrad analysis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genetic analysis of a tetrad, the products of a single meiosis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tetraploidy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the possession of four haploid sets of chromosomes (4n). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tetrasomy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Presence of two extra copies of a chromosome (2n + 2). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> TFIIB recognition element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consensus sequence [(G or C)(G or C)(G or C)CGCC] found in some RNA polymerase II core promoters; usually located from 32 to 38 bp upstream of the transcription start site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> TFIIIA transcription factor </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A eukaryotic transcription factor involved in the synthesis of 5S RNA. An interesting fact about TFIIIA is that its structure has nine zinc finger domains, making it an archetype for this class of proteins. </div> </div> </div> <div class="wrap"> <strong> the insurance hypothesis </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> If more species are present (i.e., diversity is higher), then there is a greater chance that at least one of the species will maintain functioning during disturbance or stress, compensating for other species that experience declines. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> the portfolio effect </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> If the abundance of different species fluctuates independently, or at least out of phase with one another, then these fluctuations will average each other out, leading to less variation over time in a diverse assemblage. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> theory of clonal selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Explains the generation of primary and secondary immune responses. Binding of a B cell to an antigen stimulates the cell to divide, giving rise to a clone of genetically identical cells, all of which are specific for the antigen. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> theory of island biogeography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Predicts that larger, less isolated islands will contain more species than smaller, more isolated islands; that the number of species on any island reflects a balance between the rate at which new species colonize it and the rate at which populations of established species become extinct. Proposed by Robert MacArthur and E. O. Wilson. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> therophytes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Annual plants which survive the unfavorable season in the form of seeds. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> theta replication </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Replication of circular DNA that is initiated by the unwinding of the two nucleotide strands, producing a replication bubble. Unwinding continues at one or both ends of the bubble, making it progressively larger. DNA replication on both of the template strands is simultaneous with unwinding until the two replication forks meet. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> third filial cross </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cross (mating) between individuals generated from the second generation of a parental cross (i.e., F3 = F2 x F2). </div> </div> </div> <div class="wrap"> <strong> threatened species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any species vulnerable to endangerment. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> three-point test cross </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cross between an individual heterozygous at three loci and an individual homozygous for recessive alleles at those loci. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> threshold characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Discontinuous characteristic whose expression depends on an underlying susceptibility that varies continuously. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> threshold trait </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Quantitative traits that are discretely expressed in a limited number of phenotypes (usually two), but which are based on an assumed continuous distribution of factors that contribute to the trait (underlying liability). </div> </div> </div> <div class="wrap"> <strong> thymidine kinase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An enzyme that plays a key role in the synthesis of DNA and, therefore, cell division. Often, thymidine kinase activity is used as a surrogate for measuring the rate of cell division. </div> </div> </div> <div class="wrap"> <strong> thymine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pyrimidine in DNA but not in RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Ti plasmid </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Large plasmid from the bacterium Agrobacterium tumefaciens that is used to transfer genes to plant cells. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tight linkage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes two or more loci with a low recombination frequency usually due to being physically close to one another. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> tolerance succession model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Driven by life-history characteristics whereby later succession species grow more slowly and eventually replace early succession species. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> topoisomerase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme that adds or removes rotations in a DNA helix by temporarily breaking nucleotide strands; controls the degree of DNA supercoiling. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> totipotent </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the potential of a cell to develop into any other cell type. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> trade-off </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A trait, mutation or phenotype that confers both a benefit and cost in terms of fitness. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/trait-235">trait</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An observed variation in a specific character of an organism. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> trans </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> trans-acting elements are able to diffuse through the cell and thus can affect loci on both strands of DNA in diploid or polyploid organisms </div> </div> </div> <div class="wrap"> <strong> trans configuration </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Arrangement in which each chromosome contains one wild-type (dominant) gene and one mutant (recessive) gene. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> trans-splicing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process of splicing together exons from two or more pre-mRNAs. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transcription-dna-transcription-87">transcription</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A biochemical process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA). <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> transcription bubble </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Region of a DNA molecule that has unwound to expose a single-stranded template, which is being transcribed into RNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transcription-factor-transcription-factors-167">transcription factor</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transcription factors are proteins that are involved in the process of converting, or transcribing, DNA into RNA <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> transcription factor dimerization </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When two proteins that serve to initiate gene transcription (transcription factors) must associate with each other to gain a conformation that facilitates binding to nucleic acid. </div> </div> </div> <div class="wrap"> <strong> transcription start site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The first DNA nucleotide that is transcribed into an RNA molecule. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transcription-unit-260">transcription unit</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence of nucleotides in DNA that codes for a single RNA molecule, along with the sequences necessary for its transcription; normally contains a promoter, an RNA-coding sequence, and a terminator. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transcriptional activator protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein in eukaryotic cells that binds to consensus sequences in regulatory promoters or enhancers and affects transcription initiation by stimulating or inhibiting the assembly of the basal transcription apparatus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transcriptional antiterminator protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein that binds to RNA polymerase and alters its structure so that certain terminators are ignored, allowing transcription to continue past the terminators. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transcriptome-296">transcriptome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A transcriptome is the full range of messenger RNA, or mRNA, molecules expressed by an organism </div> </div> </div> <div class="wrap"> <strong> transducing phage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Contains a piece of the bacterial chromosome inside the phage coat. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transductant </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacterial cell that has received genes from another bacterium through transduction. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transduction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Type of gene exchange that takes place when a virus carries genes from one bacterium to another. After it is inside the cell, the newly introduced DNA may undergo recombination with the bacterial chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transduction-prokaryotes-292">transduction (prokaryotes)</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transduction is a process by which a virus transfers genetic material from one bacterium to another </div> </div> </div> <div class="wrap"> <strong> transesterification </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chemical reaction in some RNA splicing reactions. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transfer RNA introns </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Class of introns in tRNA genes. Splicing of these genes relies on enzymes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transfer-messenger RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An RNA molecule that has properties of both mRNA and tRNA; functions in rescuing ribosomes that are stalled at the end of mRNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transformant-20">transformant</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cell that has received additional genetic material, either experimentally or via an infection; can be used to refer to a cell that has become malignant. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> transformation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mechanism by which DNA found in the medium is taken up by the cell. After transformation, recombination may take place between the introduced genes and the bacterial chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transformation-prokaryotes-291">transformation (prokaryotes)</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Transformation is a process by which foreign genetic material is taken up by a cell. The process results in a stable genetic change within the transformed cell </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transforming-principle-17">transforming principle</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Term given to the substance that could be transferred from non living cells to living cells, causing the living cell to show characteristics of the non living cell. This term was used by scientists in the 1930s and 1940s before they had isolated DNA and identified it as the actual transforming substance. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transgene-223">transgene</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A gene that has been transferred from the genome of one species into that of another. <div class="px10">© 2004 by Sinauer Associates, Inc. All rights reserved. Conner, J.K. and D.L. Hartl. A Primer of Ecological Genetics.</div> </div> </div> </div> <div class="wrap"> <strong> transgene escape </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The movement of a transgene into the natural population, usually when transgenic crops cross-breed with wild relatives. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> transgenic mouse </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mouse whose genome contains a foreign gene or genes added by employing recombinant DNA methods. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transgenic-organism-transgenic-36">transgenic organism</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An organism whose genome has been artifically modified; can be a microorganism or a more complex one. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> transgenic techniques </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Any method for moving a gene into the genome of a new species. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> transition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Base substitution in which a purine is replaced by a different purine or a pyrimidine is replaced by a different pyrimidine. See also point mutation, transversion. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/translation-rna-translation-173">translation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Translation is the process by which a protein is synthesized from the information contained in a molecule of messenger RNA (mRNA). </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/translocation-244">translocation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Movement of a chromosome segment to a nonhomologous chromosome or to a region within the same chromosome; also movement of a ribosome along mRNA in the course of translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> translocation carrier </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Individual organism heterozygous for a translocation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transmissible disease </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A disease that can be inherited. </div> </div> </div> <div class="wrap"> <strong> transmission genetics </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The field of genetics that encompasses the basic principles of genetics and how traits are inherited. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/transposable-element-transposon-dna-transposon-jumping-gene-52">transposable element</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mobile fragment of DNA that can change position in a genome; a cause of sequence insertions and deletions in some organisms. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> transposase </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Enzyme encoded by many types of transposable elements that is required for their transposition. The enzyme makes single-strand breaks at each end of the transposable element and on either side of the target sequence where the element inserts. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transposition </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Movement of a transposable genetic element from one site to another. Replicative transposition increases the number of copies of the transposable element; nonreplicative transposition does not increase the number of copies. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> transversion </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Base substitution in which a purine is replaced by a pyrimidine or a pyrimidine is replaced by a purine. See also point mutation, transition. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> trihybrid cross </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A cross between two individuals that differ in three characteristics (AA BB CC X aa bb cc); also refers to a cross between two individuals that are both heterozygous at three loci (Aa Bb Cc X Aa Bb Cc). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> triplet code </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the fact that three nucleotides encode each amino acid in a protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> triplo-X syndrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Human condition in which cells contain three X chromosomes. A person with triplo-X syndrome has a female phenotype without distinctive features other than a tendency to be tall and thin; a few such women are sterile, but many menstruate regularly and are fertile. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> triploidy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the possession of three haploid sets of chromosomes (3n). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/trisomy-268">trisomy</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Presence of an additional copy of a chromosome (2n + 1). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> trisomy 13 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Presence of three copies of chromosome 13; in humans, results in Patau syndrome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> trisomy 18 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Presence of three copies of chromosome 18; in humans, results in Edward syndrome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> trisomy 21 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Down syndrome; Characterized by variable degrees of mental retardation, characteristic facial features, some retardation of growth and development, and an increased incidence of heart defects, leukemia, and other abnormalities; caused by the duplication of all or part of chromosome 21 (trisomy 21). <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> trisomy 8 </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Presence of three copies of chromosome 8; in humans, results in mental retardation, contracted fingers and toes, low-set malformed ears, and a prominent forehead. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/trna-transfer-rna-256">tRNA</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> RNA molecule that carries an amino acid to the ribosome and transfers it to a growing polypeptide chain in translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tRNA charging </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Chemical reaction in which an aminoacyl-tRNA synthetase attaches an amino acid to its corresponding tRNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tRNA-modifying enzyme </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Creates a modified base in RNA by catalyzing a chemical change in the standard base. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> troposphere </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The first layer of Earth's atmosphere; it contains approximately 75% of the atmosphere's mass and 99% of its water vapor. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> truncation selection </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A breeding technique where a certain value for a selected character is set as the truncation point. Individuals on one side of the point are parents of the next generation (have high fitness) and those on the other side have no progeny (no fitness). <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Trypanosoma </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A parasitic protozoa with flagella that infects cells of animals and humans causing a variety of diseases, including sleeping sickness and Chagas' disease. </div> </div> </div> <div class="wrap"> <strong> tubulin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Protein found in microtubules. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> tumor suppressor gene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Gene that normally inhibits cell division. Recessive mutations in such genes often contribute to cancer. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Turner syndrome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Human condition in which cells contain a single X chromosome and no Y chromosome (XO). Persons with Turner syndrome are female in appearance but do not undergo puberty and have poorly developed female secondary sex characteristics; most are sterile but have normal intelligence. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/twin-study-124">twin study</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A form of experimental design in which investigators examine twins (both monozygotic and dizygotic) who were reared together or apart in order to determine the relative contributions of genetics and environment to a specific trait. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="U"><div class="padleft10px fleft bold px15">U</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> ubiquitin </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein that is post-translationally added to other proteins, frequently tagging them for proteasome-mediated degradation. </div> </div> </div> <div class="wrap"> <strong> ultrasonography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Procedure for visualizing a fetus. High-frequency sound is beamed into the uterus. Sound waves that encounter dense tissue bounce back and are transformed into a picture of the fetus. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> unbalanced data </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Data where each group does not have an equal number of data points. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> unbalanced gametes </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Gametes that have variable numbers of chromosomes; some chromosomes may be missing and others may be present in more than one copy. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> unbalanced translocation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> When pieces of chromosomes are rearranged and genetic material is gained or lost in the cell. </div> </div> </div> <div class="wrap"> <strong> underdominance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A homozygote advantage, whereby the heterozygote is selected against, resulting in more homozygous individuals. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> unequal crossing over </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Misalignment of the two DNA molecules during crossing over, resulting in one DNA molecule with an insertion and the other with a deletion. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> uniparental disomy </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Inheritance of both chromosomes of a homologous pair from a single parent. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> unique-sequence DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence present only once or a few times in a genome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> universal genetic code </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Refers to the fact that particular codons specify the same amino acids in almost all organisms. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> unlinked loci </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genes with a recombination frequency of 0.5 that therefore sort independently. Genes on separate chromosomes or physically far apart on large chromosomes. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> unstable equilibrium </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A system that will not return to the original state after a disturbance. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> untranslated region </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Part of an mRNA sequence that is not included as a template for the production of a protein. </div> </div> </div> <div class="wrap"> <strong> up mutation </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Mutation that increases the rate of transcription. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> upstream </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Toward the 5' end of a chain of nucleotides. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> upstream control element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consensus sequence in eukaryotic RNA polymerase I promoters that extends from 107 to 180 bp upstream of the transcription start site and increases the efficiency of the core element; rich in guanine and cytosine nucleotides. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> upstream element </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consensus sequence found in some bacterial promoters that contains a number of A-T pairs and is found about 40 to 60 bp upstream of the transcription start site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> uracil </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Pyrimidine in RNA but not normally in DNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="V"><div class="padleft10px fleft bold px15">V</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> variable </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Some factor, such as number or a trait, that is likely to change or vary; something measureable yet dynamic, such that measurements change depending on impacting forces, such as the passage of time or environmental conditions. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> variable expression </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Differences between individuals in how a trait manifests itself. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/variable-number-tandem-repeats-vntrs-vntr-238">variable number tandem repeats</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Within a gene, short sequences of DNA repeated in tandem that vary greatly in number among individuals; also called microsatellites. Commonly used in DNA fingerprinting due to extreme variability among humans; abbreviated as VNTRs. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> variance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A measure of the spread of a set of numerical observations; calculated as the average of the squared deviation from the mean. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> vector </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A piece of DNA that ferries a foreign seqence of DNA into a cell or organism; together with the foreign DNA, the vector forms recombinant DNA. In disease transmission, the organism that carries an infectious agent (virus, parasite) from one host to another. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> vector-borne diseases </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Diseases in which the pathogenic microorganism is transmitted from an infected individual to another individual by an arthropod or other agent, sometimes with other animals serving as intermediary hosts. Nearly half of the world.s population is infected by vector-borne diseases, resulting in high morbidity and mortality. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> vegetative reproduction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cloning of plants by asexual means; especially in plans, new individuals develop asexually from specialized structures such as bulbs, rhizomes, or runners rather than from specialized sex cells. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> verbal model </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A display of relationships expressed in words instead of mathematical formula. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> vertical transmission </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The transfer of a condition or disease from one generation to another via genetics or parent to child contact. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> vestigial </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes something occurring in a simpler, less functional state; sometimes a remnant of a larger more robust form. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> viability </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The ability to live. May refer to the number of a cohort surviving to a given age. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> vicariance </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process whereby environmental changes divide a population into separate isolated groups. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> vicariance species </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> To occur in a location because their ancestors remained there passively as the environment moved around them. <div class="px10">© 2010 by Nature Education Knowledge.</div> </div> </div> </div> <div class="wrap"> <strong> virulence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The degree of pathogenicity. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/virulence-factor-53">virulence factor</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> An intrinsic character of infectious bacteria that facilitates its ability to cause disease. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> virulent phage </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Bacteriophage that reproduces only through the lytic cycle and kills its host cell. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/virus-308">virus</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A virus is an infectious agent that can replicate only within a host organism. Viruses infect a variety of living organisms, including bacteria, plants, and animals <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> visible polymorphism </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes a trait with only a few distinct versions. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> vulva </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In humans, the external genitals of females; in nematodes, an orifice found in the ventral epidermis that facilitates egg-laying and mating. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="W"><div class="padleft10px fleft bold px15">W</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> weather </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The state of the atmosphere at any given time, including measures such as temperature, rain, cloud cover, wind and humidity. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/western-blot-288">Western blot</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A Western blot is a laboratory method used to detect specific proteins from a mixture of proteins <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> Western blotting </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Process by which protein is transferred from a gel to a solid support such as a nitrocellulose or nylon filter. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> wheat embryo cell-free translation system </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mixture extracted from wheat embryos that has all of the molecules needed to make a protein when an mRNA is added. <div class="px10">Jon Moulton</div> </div> </div> </div> <div class="wrap"> <strong> whole-genome shotgun sequencing </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method of sequencing a genome in which sequenced fragments are assembled into the correct sequence in contigs by using only the overlaps in sequence. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> wiggle format </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In bioinformatics, the display format for dense continuous data such a guanine-cytosine content, probability scores, and transcriptome data; abbreviated as WIG. <div class="px10"> © Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> wild type </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The commonly occurring allele or characteristic in a natural population. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> wild-type allele </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The most prevalent allele in a natural population for a certain gene. <div class="px10">© 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/wobble-191">wobble</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Describes the redundancy in the genetic code such that the same amino acid may be encoded by multiple codons. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="X"><div class="padleft10px fleft bold px15">X</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/x-chromosome-96">X chromosome</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of the two sex chromosomes in animals that are determined by the XX-XY system; the only sex chromosome in animals whose sex is determined by the XX-XO system. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/x-inactivation-x-inactivation-233">X inactivation</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The process and result of one of a pair of X chromosomes becoming silent or inactive in a female mammal; typically occurs in early embryonic development and affects the life of the female. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> X-linked characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Characteristic determined by a gene or genes on the X chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> X-ray crystallography </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A method to determine the three-dimensional organization of biochemicals. Generally, crystals of a molecule are used because they are an array of many molecules of the same compound, thus increasing the strength of diffraction of the X-rays. </div> </div> </div> <div class="wrap"> <strong> X-ray diffraction </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Method for analyzing the three-dimensional shape and structure of chemical substances. Crystals of a substance are bombarded with X-rays, which hit the crystals, bounce off, and produce a diffraction pattern on a detector. The pattern of the spots produced on the detector provides information about the molecular structure. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> X-Y homologs </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Y-linked genes that are similar to genes on the X chromosome. </div> </div> </div> <div class="wrap"> <strong> X:A ratio </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Ratio of the number of X chromosomes to the number of haploid autosomal sets of chromosomes; determines sex in fruit flies. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> Xist RNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The RNA that coats the inactive X chromosome. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/xx-xo-system-85">XX-XO system</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In organisms like crickets, grasshoppers, and some other insects, the female is XX and is the homogametic sex. The male is the heterogametic sex but only has one sex chromosome. The male in XX-XO systems produce gametes with (X) or without (O) a sex chromosome. </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/xx-xy-system-180">XX-XY system</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In organisms like humans and mammals, the male is the heterogametic sex, producing gametes with either an X or a Y chromosome. All gametes from the female are X. Thus, the sex of the offspring is determined by the class of sperm. </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="Y"><div class="padleft10px fleft bold px15">Y</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> Y chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> One of two sex chromosomes in organisms that are defined by the XX-XY sex determination system. Y chromosomes are unique to males in this system. </div> </div> </div> <div class="wrap"> <strong> Y-linked </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Genes located on the Y chromosome. </div> </div> </div> <div class="wrap"> <strong> Y-linked characteristic </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Characteristic determined by a gene or genes on the Y chromosome. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/yeast-267">yeast</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Baker's yeast, one of the simplest eukaryotes, serves as a valuable model organism, particularly in studies of cell division. </div> </div> </div> <div class="wrap"> <strong> yeast artificial chromosome </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Cloning vector consisting of a DNA molecule with a yeast origin of replication, a pair of telomeres, and a centromere. YACs can carry very large pieces of DNA (as large as several hundred thousand base pairs) and replicate and segregate like yeast chromosomes. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> yellow fluorescent protein </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A mutant version of green fluorescent protein that can be used as a reporter construct in live cells. </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="Z"><div class="padleft10px fleft bold px15">Z</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> Z-DNA </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Secondary structure of DNA characterized by 12 bases per turn, a left-handed helix, and a sugar-phosphate backbone that zigzags back and forth. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> zinc finger </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A protein motif consisting of an alpha helix and an anti-parallel beta sheet. Specific amino acids in the helix and sheet interact with a zinc atom, resulting in a finger-like structure. </div> </div> </div> <div class="wrap"> <strong> zygote </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The resulting diploid cell from the fusion of two haploid gametes, the result of sexual reproduction. <div class="px10"> © 2014 Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> zygote intrafallopian transfer </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The method of transferring an ovum fertilized in vitro to a woman's uterine tube, to assist in human reproduction. <div class="px10">© Nature Education</div> </div> </div> </div> <div class="wrap"> <strong> zygotene </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Second substage of prophase I in meiosis. In zygotene, chromosomes enter into synapsis. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> <a class="inlineLinks" href="/scitable/definition/zz-zw-system-217">ZZ-ZW system</a> </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> In some birds, butterflies, moths, and other organisms, the female is the heterogametic sex. These females are designated ZW, while the males are ZZ. </div> </div> </div> <div class="wrap-in"> <div border="0"> <strong class="barcolor clearfix pad5px marginbot20px h15" id="othrsLnkGlo"><div class="padleft10px fleft bold px15">Others</div><div class="fright"><span><a class="inlineLinks" href="#" title="Return to Top">TOP</a></span></div></strong> </div> </div> <div class="wrap"> <strong> -10 consensus sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consensus sequence (TATAAT) found in most bacterial promoters approximately 10 bp upstream of the transcription start site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> -35 consensus sequence </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Consensus sequence (TTGACA) found in many bacterial promoters approximately 35 bp upstream of the transcription start site. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 10T1/2 cell line </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A contact-inhibited fibroblastic cell line derived from a mouse embryo that is commonly used for toxicity screening, transfection, transformation, tumorigenicity, and cloning studies. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> 3' end </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> End of the polynucleotide chain in which an OH group is attached to the 3'-carbon atom of the nucleotide. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 3' splice site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The 3' end of an intron where cleavage takes place in RNA splicing. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 3' untranslated (UTR) region </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence of nucleotides at the 3' end of mRNA; does not code for the amino acids of a protein but affects both the stability of the mRNA and its translation. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition..</div> </div> </div> </div> <div class="wrap"> <strong> 30S initiation complex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Initial complex formed in the initiation of translation in bacterial cells; consists of the small subunit of the ribosome, mRNA, initiator tRNA charged with fMet, GTP, and initiation factors 1, 2, and 3. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 5' cap </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Modified 5' end of eukaryotic mRNA, consisting of an extra nucleotide (methylated) and methylation of the 2' position of the sugar in one or more subsequent nucleotides; plays a role in the binding of the ribosome to mRNA and affects mRNA stability and the removal of introns. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 5' end </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> End of the polynucleotide chain in which a phosphate is attached to the 5'-carbon atom of the nucleotide. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 5' splice site </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> The 5' end of an intron where cleavage takes place in RNA splicing. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 5' untranslated (UTR) region </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Sequence of nucleotides at the 5' end of mRNA; does not code for the amino acids of a protein. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 5'-methylcytosine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Modified nucleotide, consisting of cytosine to which a methyl group has been added; predominate form of methylation in eukaryotic DNA. <div class="px10">© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.</div> </div> </div> </div> <div class="wrap"> <strong> 5-azacytidine </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> A chemical that can effectively remove the methyl groups from nucleic acids. <div class="px10"> </div> </div> </div> </div> <div class="wrap"> <strong> 70S initiation complex </strong> <div class="clearfix marginbot15px"> <div class="fleft w728"> Final complex formed in the initiation of translation in bacterial cells; consists of the small and large subunits of the ribosome, mRNA, and initiator tRNA charged with fMet. <div class="px10"> </div> </div> </div> </div> <div class="cleartboth"></div> </div> </div> <div class="leftRail" id="leftRail"> <div id="zoneForProductsDivID" class="leftRailContent" style="display:none;"> </div> <div class="leftRailContent"> <div class="lrContentHead"> <img alt="Topics" src="/scitable/natedimages/topic_leftNav.jpg"/> </div> <div class="leftRailSection lastSection clearfix"> <span class="redArrow padleft8px clear w130"> <a href="/scitable/topic/genetics-5" class="inlineLinks"> Genetics </a> </span> <div class="clear" style="height:0px;line-height: 0px !important;font-size: 0px;"></div> <ul class="vertIndentList" style="display:none"> <li> <a href="/scitable/topic/gene-inheritance-and-transmission-23"> Gene Inheritance and Transmission </a> </li> <li> <a href="/scitable/topic/gene-expression-and-regulation-15"> Gene Expression and Regulation </a> </li> <li> <a href="/scitable/topic/nucleic-acid-structure-and-function-9"> Nucleic Acid Structure and Function </a> </li> <li> <a href="/scitable/topic/chromosomes-and-cytogenetics-7"> Chromosomes and Cytogenetics </a> </li> <li> <a href="/scitable/topic/evolutionary-genetics-13"> Evolutionary Genetics </a> </li> <li> <a href="/scitable/topic/population-and-quantitative-genetics-21"> Population and Quantitative Genetics </a> </li> <li> <a href="/scitable/topic/genomics-19"> Genomics </a> </li> <li> <a href="/scitable/topic/genes-and-disease-17"> Genes and Disease </a> </li> <li> <a href="/scitable/topic/genetics-and-society-11"> Genetics and Society </a> </li> </ul> <div class="clear" style="height:0px;line-height: 0px !important;font-size: 0px;"></div> <span class="redArrow padleft8px clear w130"> <a href="/scitable/topic/cell-biology-13906536" class="inlineLinks"> Cell Biology </a> </span> <div class="clear" style="height:0px;line-height: 0px !important;font-size: 0px;"></div> <ul class="vertIndentList" style="display:none"> <li> <a href="/scitable/topic/cell-origins-and-metabolism-14122694"> Cell Origins and Metabolism </a> </li> <li> <a href="/scitable/topic/proteins-and-gene-expression-14122688"> Proteins and Gene Expression </a> </li> <li> <a href="/scitable/topic/subcellular-compartments-14122679"> Subcellular Compartments </a> </li> <li> <a href="/scitable/topic/cell-communication-14122659"> Cell Communication </a> </li> <li> <a href="/scitable/topic/cell-cycle-and-cell-division-14122649"> Cell Cycle and Cell Division </a> </li> </ul> <div class="clear" style="height:0px;line-height: 0px !important;font-size: 0px;"></div> <span class="redArrow padleft8px clear w130"> <a href="/scitable/topic/scientific-communication-14121566" class="inlineLinks"> Scientific Communication </a> </span> <div class="clear" style="height:0px;line-height: 0px !important;font-size: 0px;"></div> <ul class="vertIndentList" style="display:none"> </ul> <div class="clear" style="height:0px;line-height: 0px !important;font-size: 0px;"></div> <span class="redArrow padleft8px clear w130"> <a href="/scitable/topic/career-planning-14121550" class="inlineLinks"> Career Planning </a> </span> <div class="clear" style="height:0px;line-height: 0px !important;font-size: 0px;"></div> <ul class="vertIndentList" style="display:none"> </div> </div> <br class="clear hide"/> <div class="leftRailContent" id="leftDashboardPlaceID" style="display:none"> <div class="lrContentHead"> <img src="/scitable/natedimages/updateLR.gif" alt="Updates"> </div> <div> <div class="horzAlignCenter padleft10px" id="leftDashboardID"> <img src="/scitable/natedimages/ajaxLoader.gif" class="padleft10px"> <span class="padleft10px bold customContentRestHdr">Loading ...</span> <br/><br/> </div> </div> </div> <div class="leftRailContent"> <div class="lrContentHead communityHead"><img src="/scitable/natedimages/connect.gif" alt="Connect" /></div> <div class=""> <img src="/scitable/natedimages/connectLeftRailImg.gif" alt="Connect" usemap="#leftRailConnect" /> <map id="Connect" name="leftRailConnect"> <area shape="rect" coords="66,66,98,86" href="#" id="SendCommonMessage" name="SendCommonMessage" onClick="signInToSendCommonMessage(event);" title="Send a message" alt="Send a message" /> </map> </div> </div> <div id='div-gpt-ad-1403213733612-2'> <script type='text/javascript'> googletag.cmd.push(function() { googletag.display('div-gpt-ad-1403213733612-2'); 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