Inheritance | Biology | Visionlearning

<!DOCTYPE html> <html lang="en" dir="ltr"> <head>  <meta http-equiv="X-UA-Compatible" content="ie=edge"> <meta charset="utf-8"> <base href="https://www.visionlearning.com"> <title>Inheritance | Biology | Visionlearning</title> <link rel="canonical" href="https://www.visionlearning.com/en/library/Biology/2/Mendel-and-Inheritance/129"> <meta name="description" content="Learn about Mendel's Law of Inheritance, confirming that traits are passed from two parents in a predictable pattern. Includes information about dominant and recessive genes"> <meta name="keywords" content="how are genes passed, what is a trait, difference between dominant and recessive, Punnet squares, hybridization"> <meta name="viewport" content="width=device-width, initial-scale=1.0, shrink-to-fit=no"> <meta name="msvalidate.01" content="D8E20F39AD48052260032E56DE409970"> <script type="application/ld+json"> { "@context": "http://schema.org/", "@type": "Article", "mainEntityOfPage": { "@type": "WebPage", "@id": "https://visionlearning.com/en/library/Biology/2/Mendel-and-Inheritance/129" }, "name": "Inheritance", "headline": "Inheritance: Mendel's experiments and laws", "author": { "@type": "Person", "name": "Natalie H. Kuldell" }, "datePublished": "2005-03-29 13:40:45", "dateModified": "2017-02-12T08:30:00+05:00", "image": { "@type": "ImageObject", "url": "/img/library/moduleImages/featured_image_129-23061209063555.jpg", "width": 696, "height": 464 }, "publisher": { "@type": "Organization", "name": "Visionlearning, Inc.", "logo": { "@type": "ImageObject", "url": "http://visionlearning.com/images/logo.png", "width": 278, "height": 60 } }, "description": "Inheritance patterns have been of interest since ancient times, but it was Gregor Mendel's work in the mid-1800s that confirmed that traits are passed on by two parents in a predictable pattern. This module describes the experiments that resulted in <em>Mendel's Laws of Inheritance</em>. A look at specific traits in pea plants over generations shows how Mendel's research methods resulted in an understanding of dominant and recessive genes. Partial dominance is also discussed.", "keywords": "how are genes passed, what is a trait, difference between dominant and recessive, Punnet squares, hybridization", "inLanguage": { "@type": "Language", "name": "English", "alternateName": "en" }, "copyrightHolder": { "@type": "Organization", "name": "Visionlearning, Inc." }, "copyrightYear": "2005"} </script> <meta property="og:url" content="https://visionlearning.com/en/library/Biology/2/Mendel-and-Inheritance/129"> <meta property="og:title" content="Inheritance | Biology | Visionlearning" /> <meta property="og:type" content="website"> <meta property="og:site_name" content="Visionlearning"> <meta property="og:description" content="Learn about Mendel's Law of Inheritance, confirming that traits are passed from two parents in a predictable pattern. 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class="accordion__panel" id="acc-panel-genetics" data-accordion="panel" aria-labelledby="acc-button-genetics" role="region"> <ul class="nav text-color-link"> <li class="current">Inheritance</li> <li><a href="/en/library/biology/2/independent-assortment/145">Independent Assortment</a></li> <li><a href="/en/library/biology/2/dna-i/149">DNA I</a></li> <li><a href="/en/library/biology/2/dna-ii/160">DNA II</a></li> <li><a href="/en/library/biology/2/dna-iii/180">DNA III</a></li> <li><a href="/en/library/biology/2/tracking-human-ancestry/248">Tracking Human Ancestry</a></li> <li><a href="/en/library/biology/2/gene-expression/214">Gene Expression</a></li> <li><a href="/en/library/biology/2/population-genetics/249">Population Genetics</a></li> </ul> </div> <button class="accordion__button" id="acc-button-ecology" data-accordion="button" aria-controls="acc-panel-ecology" aria-expanded="false"> <span class="accordion__button__label"> Ecology </span> </button> <div class="accordion__panel" 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Services</a></li> <li><a href="/en/library/environmental-science/61/population-biology/287">Population Biology</a></li> </ul> </div> <button class="accordion__button" id="acc-button-earth-cycles" data-accordion="button" aria-controls="acc-panel-earth-cycles" aria-expanded="false"> <span class="accordion__button__label"> Earth Cycles </span> </button> <div class="accordion__panel" id="acc-panel-earth-cycles" data-accordion="panel" aria-labelledby="acc-button-earth-cycles" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/the-nitrogen-cycle/98">The Nitrogen Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-carbon-cycle/95">The Carbon Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-phosphorus-cycle/197">The Phosphorus Cycle</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/environmental-science/61/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-general-science" data-accordion="button" aria-controls="acc-panel-general-science" aria-expanded="false"> <span class="accordion__button__label"> General Science </span> </button> <div class="accordion__panel" id="acc-panel-general-science" data-accordion="panel" aria-labelledby="acc-button-general-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-methods" data-accordion="button" aria-controls="acc-panel-methods" aria-expanded="false"> <span class="accordion__button__label"> Methods </span> </button> <div class="accordion__panel" id="acc-panel-methods" data-accordion="panel" aria-labelledby="acc-button-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-scientific-method/45">The Scientific Method</a></li> </ul> </div> <button class="accordion__button" id="acc-button-measurement" data-accordion="button" aria-controls="acc-panel-measurement" aria-expanded="false"> <span class="accordion__button__label"> Measurement </span> </button> <div class="accordion__panel" id="acc-panel-measurement" data-accordion="panel" aria-labelledby="acc-button-measurement" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-metric-system/47">The Metric System</a></li> </ul> </div> <button class="accordion__button" id="acc-button-physical-properties" data-accordion="button" aria-controls="acc-panel-physical-properties" aria-expanded="false"> <span class="accordion__button__label"> Physical Properties </span> </button> <div class="accordion__panel" id="acc-panel-physical-properties" data-accordion="panel" aria-labelledby="acc-button-physical-properties" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/temperature/48">Temperature</a></li> <li><a href="/en/library/general-science/3/density-and-buoyancy/37">Density and Buoyancy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-math-in-science" data-accordion="button" aria-controls="acc-panel-math-in-science" aria-expanded="false"> <span class="accordion__button__label"> Math in Science </span> </button> <div class="accordion__panel" 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href="/en/library/math-in-science/62/scientific-notation/250">Scientific Notation</a></li> <li><a href="/en/library/math-in-science/62/measurement/257">Measurement</a></li> </ul> </div> <button class="accordion__button" id="acc-button-statistics" data-accordion="button" aria-controls="acc-panel-statistics" aria-expanded="false"> <span class="accordion__button__label"> Statistics </span> </button> <div class="accordion__panel" id="acc-panel-statistics" data-accordion="panel" aria-labelledby="acc-button-statistics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/introduction-to-descriptive-statistics/218">Introduction to Descriptive Statistics</a></li> <li><a href="/en/library/math-in-science/62/introduction-to-inferential-statistics/224">Introduction to Inferential Statistics</a></li> <li><a href="/en/library/math-in-science/62/statistical-techniques/239">Statistical Techniques</a></li> </ul> </div> <button class="accordion__button" id="acc-button-trigonometric-functions" data-accordion="button" aria-controls="acc-panel-trigonometric-functions" aria-expanded="false"> <span class="accordion__button__label"> Trigonometric Functions </span> </button> <div class="accordion__panel" id="acc-panel-trigonometric-functions" data-accordion="panel" aria-labelledby="acc-button-trigonometric-functions" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/wave-mathematics/131">Wave Mathematics</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-physics" data-accordion="button" aria-controls="acc-panel-physics" aria-expanded="false"> <span class="accordion__button__label"> Physics </span> </button> <div class="accordion__panel" id="acc-panel-physics" data-accordion="panel" aria-labelledby="acc-button-physics" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-light-and-optics" data-accordion="button" aria-controls="acc-panel-light-and-optics" aria-expanded="false"> <span class="accordion__button__label"> Light and Optics </span> </button> <div class="accordion__panel" id="acc-panel-light-and-optics" data-accordion="panel" aria-labelledby="acc-button-light-and-optics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/the-nature-of-light/132">The Nature of Light</a></li> <li><a href="/en/library/physics/24/electromagnetism-and-light/138">Electromagnetism and Light</a></li> </ul> </div> <button class="accordion__button" id="acc-button-mechanics" data-accordion="button" aria-controls="acc-panel-mechanics" aria-expanded="false"> <span class="accordion__button__label"> Mechanics </span> </button> <div class="accordion__panel" id="acc-panel-mechanics" data-accordion="panel" aria-labelledby="acc-button-mechanics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/defining-energy/199">Defining Energy</a></li> <li><a href="/en/library/physics/24/waves-and-wave-motion/102">Waves and Wave Motion</a></li> <li><a href="/en/library/physics/24/gravity/118">Gravity</a></li> <li><a href="/en/library/physics/24/thermodynamics-i/200">Thermodynamics I</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-process-of-science" data-accordion="button" aria-controls="acc-panel-process-of-science" aria-expanded="false"> <span class="accordion__button__label"> Process of Science </span> </button> <div class="accordion__panel" id="acc-panel-process-of-science" data-accordion="panel" aria-labelledby="acc-button-process-of-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-introduction" data-accordion="button" aria-controls="acc-panel-introduction" aria-expanded="false"> <span class="accordion__button__label"> Introduction </span> </button> <div class="accordion__panel" id="acc-panel-introduction" data-accordion="panel" aria-labelledby="acc-button-introduction" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-process-of-science/176">The Process of Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-the-culture-of-science" data-accordion="button" aria-controls="acc-panel-the-culture-of-science" aria-expanded="false"> <span class="accordion__button__label"> The Culture of Science </span> </button> <div class="accordion__panel" id="acc-panel-the-culture-of-science" data-accordion="panel" aria-labelledby="acc-button-the-culture-of-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-nature-of-scientific-knowledge/185">The Nature of Scientific Knowledge</a></li> <li><a href="/en/library/process-of-science/49/scientists-and-the-scientific-community/172">Scientists and the Scientific Community</a></li> <li><a href="/en/library/process-of-science/49/scientific-ethics/161">Scientific Ethics</a></li> <li><a href="/en/library/process-of-science/49/scientific-institutions-and-societies/162">Scientific Institutions and Societies</a></li> </ul> </div> <button class="accordion__button" id="acc-button-ideas-in-science" data-accordion="button" aria-controls="acc-panel-ideas-in-science" aria-expanded="false"> <span class="accordion__button__label"> Ideas in Science </span> </button> <div class="accordion__panel" id="acc-panel-ideas-in-science" data-accordion="panel" aria-labelledby="acc-button-ideas-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/theories-hypotheses-and-laws/177">Theories, Hypotheses, and Laws</a></li> <li><a href="/en/library/process-of-science/49/scientific-controversy/181">Scientific Controversy</a></li> <li><a href="/en/library/process-of-science/49/creativity-in-science/182">Creativity in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-research-methods" data-accordion="button" aria-controls="acc-panel-research-methods" aria-expanded="false"> <span class="accordion__button__label"> Research Methods </span> </button> <div class="accordion__panel" id="acc-panel-research-methods" data-accordion="panel" aria-labelledby="acc-button-research-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-practice-of-science/148">The Practice of Science</a></li> <li><a href="/en/library/process-of-science/49/experimentation-in-scientific-research/150">Experimentation in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/description-in-scientific-research/151">Description in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/comparison-in-scientific-research/152">Comparison in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/modeling-in-scientific-research/153">Modeling in Scientific Research</a></li> </ul> </div> <button class="accordion__button" id="acc-button-data" data-accordion="button" aria-controls="acc-panel-data" aria-expanded="false"> <span class="accordion__button__label"> Data </span> </button> <div class="accordion__panel" id="acc-panel-data" data-accordion="panel" aria-labelledby="acc-button-data" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/data-analysis-and-interpretation/154">Data Analysis and Interpretation</a></li> <li><a href="/en/library/process-of-science/49/uncertainty-error-and-confidence/157">Uncertainty, Error, and Confidence</a></li> <li><a href="/en/library/process-of-science/49/statistics-in-science/155">Statistics in Science</a></li> <li><a href="/en/library/process-of-science/49/using-graphs-and-visual-data-in-science/156">Using Graphs and Visual Data in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-communication" data-accordion="button" aria-controls="acc-panel-scientific-communication" aria-expanded="false"> <span class="accordion__button__label"> Scientific Communication </span> </button> <div class="accordion__panel" id="acc-panel-scientific-communication" data-accordion="panel" aria-labelledby="acc-button-scientific-communication" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/understanding-scientific-journals-and-articles/158">Understanding Scientific Journals and Articles</a></li> <li><a href="/en/library/process-of-science/49/utilizing-the-scientific-literature/173">Utilizing the Scientific Literature</a></li> <li><a href="/en/library/process-of-science/49/peer-review-in-scientific-publishing/159">Peer Review in Scientific Publishing</a></li> <li><a href="/en/library/process-of-science/49/the-how-and-why-of-scientific-meetings/186">The How and Why of Scientific Meetings</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-scientists-and-research" data-accordion="button" aria-controls="acc-panel-scientists-and-research" aria-expanded="false"> <span class="accordion__button__label"> Scientists and Research </span> </button> <div class="accordion__panel" id="acc-panel-scientists-and-research" data-accordion="panel" aria-labelledby="acc-button-scientists-and-research" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/scientists-and-research/58/from-stable-chromosomes-to-jumping-genes/184">From Stable Chromosomes to Jumping Genes</a></li> <li><a href="/en/library/scientists-and-research/58/an-elegant-experiment-to-test-the-process-of-dna-replication/187">An Elegant Experiment to Test the Process of DNA Replication</a></li> <li><a href="/en/library/scientists-and-research/58/the-founding-of-neuroscience/233">The Founding of Neuroscience</a></li> <li><a href="/en/library/scientists-and-research/58/tracking-endangered-jaguars-across-the-border/189">Tracking Endangered Jaguars across the Border</a></li> <li><a href="/en/library/scientists-and-research/58/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> <li><a href="/en/library/scientists-and-research/58/revolutionizing-medicine-with-monoclonal-antibodies/220">Revolutionizing Medicine with Monoclonal Antibodies</a></li> <li><a href="/en/library/scientists-and-research/58/uncovering-the-mysteries-of-chronic-mountain-sickness/238">Uncovering the Mysteries of Chronic Mountain Sickness</a></li> </ul> </div> <button class="accordion__button" id="acc-button-profiles-in-science" data-accordion="button" aria-controls="acc-panel-profiles-in-science" aria-expanded="false"> <span class="accordion__button__label"> Profiles in Science </span> </button> <div class="accordion__panel" id="acc-panel-profiles-in-science" data-accordion="panel" aria-labelledby="acc-button-profiles-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/luis-e.-miramontes/232">Luis E. Miramontes</a></li> <li><a href="/en/library/scientists-and-research/58/bernardo-houssay/237">Bernardo Houssay</a></li> <li><a href="/en/library/scientists-and-research/58/craig-lee/256">Craig Lee</a></li> <li><a href="/en/library/scientists-and-research/58/david-ho/241">David Ho</a></li> <li><a href="/en/library/scientists-and-research/58/louis-tompkins-wright/244">Louis Tompkins Wright</a></li> <li><a href="/en/library/scientists-and-research/58/carlos-j.-finlay/217">Carlos J. Finlay</a></li> <li><a href="/en/library/scientists-and-research/58/cecilia-payne/290">Cecilia Payne</a></li> <li><a href="/en/library/scientists-and-research/58/jazmin-scarlett/291">Jazmin Scarlett</a></li> <li><a href="/en/library/scientists-and-research/58/ramari-stewart/292">Ramari Stewart</a></li> <li><a href="/en/library/scientists-and-research/58/johnson-cerda/300">Johnson Cerda</a></li> <li><a href="/en/library/scientists-and-research/58/ellen-ochoa/201">Ellen Ochoa</a></li> <li><a href="/en/library/scientists-and-research/58/ruth-benerito/205">Ruth Benerito</a></li> <li><a href="/en/library/scientists-and-research/58/franklin-chang-díaz/219">Franklin Chang Díaz</a></li> <li><a href="/en/library/scientists-and-research/58/percy-lavon-julian/221">Percy Lavon Julian</a></li> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229">Luis Walter Alvarez</a></li> <li><a href="/en/library/scientists-and-research/58/france-anne-dominic-córdova/230">France Anne-Dominic Córdova</a></li> </ul> </div> </div> </div> </div> </div> </li> <li>  <button class="button" data-toggle="dropdown">Biology </button> <div class="nav__dropdown box-shadow-1 padding-1"> <div class="accordion accordion--secondary font-size-sm"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-sub-button-biological-molecules" data-accordion="button" aria-controls="acc-sub-panel-biological-molecules" aria-expanded="false"> <span class="accordion__button__label"> Biological Molecules </span> </button> <div class="accordion__panel" id="acc-sub-panel-biological-molecules" data-accordion="panel" aria-labelledby="acc-sub-button-biological-molecules" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/biology/2/carbohydrates/61">Carbohydrates</a></li> <li><a href="/en/library/biology/2/fats-and-proteins/62">Fats and Proteins</a></li> <li><a href="/en/library/biology/2/biological-proteins/243">Biological Proteins</a></li> <li><a href="/en/library/biology/2/blood-biology-i/242">Blood Biology I</a></li> <li><a href="/en/library/biology/2/lipids/207">Lipids</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-cell-biology" data-accordion="button" aria-controls="acc-sub-panel-cell-biology" aria-expanded="false"> <span class="accordion__button__label"> Cell Biology </span> </button> <div class="accordion__panel" id="acc-sub-panel-cell-biology" data-accordion="panel" aria-labelledby="acc-sub-button-cell-biology" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/biology/2/discovery-and-structure-of-cells/64">Discovery and Structure of Cells</a></li> <li><a href="/en/library/biology/2/respiration/285">Respiration</a></li> <li><a href="/en/library/biology/2/membranes-i/198">Membranes I</a></li> <li><a href="/en/library/biology/2/membranes-ii/204">Membranes II</a></li> <li><a href="/en/library/biology/2/cellular-organelles-i/195">Cellular Organelles I</a></li> <li><a href="/en/library/biology/2/cell-division-i/196">Cell Division I</a></li> <li><a href="/en/library/biology/2/cell-division-ii/212">Cell Division II</a></li> <li><a href="/en/library/biology/2/membranes-and-chemical-transport/106">Membranes and Chemical Transport</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-energy-in-living-systems" data-accordion="button" aria-controls="acc-sub-panel-energy-in-living-systems" aria-expanded="false"> <span class="accordion__button__label"> Energy in Living Systems </span> </button> <div class="accordion__panel" id="acc-sub-panel-energy-in-living-systems" data-accordion="panel" aria-labelledby="acc-sub-button-energy-in-living-systems" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/biology/2/energy-metabolism-i/215">Energy Metabolism I</a></li> <li><a href="/en/library/biology/2/energy-metabolism-ii/225">Energy Metabolism II</a></li> <li><a href="/en/library/biology/2/photosynthesis-i/192">Photosynthesis I</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-evolutionary-biology" data-accordion="button" aria-controls="acc-sub-panel-evolutionary-biology" aria-expanded="false"> <span class="accordion__button__label"> Evolutionary Biology </span> </button> <div class="accordion__panel" id="acc-sub-panel-evolutionary-biology" data-accordion="panel" aria-labelledby="acc-sub-button-evolutionary-biology" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/biology/2/origins-of-life-i/226">Origins of Life I</a></li> <li><a href="/en/library/biology/2/origins-of-life-ii/227">Origins of Life II</a></li> <li><a href="/en/library/biology/2/extinction/295">Extinction</a></li> <li><a href="/en/library/biology/2/mass-extinctions/294">Mass Extinctions</a></li> <li><a href="/en/library/biology/2/charles-darwin-i/110">Charles Darwin I</a></li> <li><a href="/en/library/biology/2/charles-darwin-ii/111">Charles Darwin II</a></li> <li><a href="/en/library/biology/2/charles-darwin-iii/112">Charles Darwin III</a></li> <li><a href="/en/library/biology/2/adaptation/68">Adaptation</a></li> <li><a href="/en/library/biology/2/taxonomy-i/70">Taxonomy I</a></li> <li><a href="/en/library/biology/2/taxonomy-ii/89">Taxonomy II</a></li> <li><a href="/en/library/biology/2/introduction-to-paleoanthropology/258">Introduction to Paleoanthropology</a></li> <li><a href="/en/library/biology/2/the-piltdown-hoax/263">The Piltdown Hoax</a></li> <li><a href="/en/library/biology/2/future-of-human-evolution/259">Future of Human Evolution</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-genetics" data-accordion="button" aria-controls="acc-sub-panel-genetics" aria-expanded="false"> <span class="accordion__button__label"> Genetics </span> </button> <div class="accordion__panel" id="acc-sub-panel-genetics" data-accordion="panel" 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aria-labelledby="acc-sub-button-ecology" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/biology/2/biodiversity-i/276">Biodiversity I</a></li> <li><a href="/en/library/biology/2/ecosystem-services/279">Ecosystem Services</a></li> <li><a href="/en/library/biology/2/animal-ecology/283">Animal Ecology</a></li> <li><a href="/en/library/biology/2/biodiversity-ii/281">Biodiversity II</a></li> <li><a href="/en/library/biology/2/animal-behavior/286">Animal Behavior</a></li> <li><a href="/en/library/biology/2/population-biology/287">Population Biology</a></li> <li><a href="/en/library/biology/2/trophic-ecology/293">Trophic Ecology</a></li> </ul> </div> </div> </div> </div> </li> </ul> </nav>  <div id="theTop"></div> <main id="skip-header-content"> <div class="margin-bottom-5"> <article class="container wide module"> <header class="grid grid--sidebar-right module__header"> <div class="module__header__title"> <span class="subcategory"> <strong><em>Genetics</em></strong> </span> <h1>Inheritance: <sub><em>Mendel's experiments and laws</em></sub></h1> <p class="byline">by Natalie H. Kuldell</p> <nav class="module__header__tabs"> <ul class="tabs-nav tabs-nav--horizontal library"> <li> <a href="/en/library/Biology/2/Mendel-and-Inheritance/129/reading" aria-current="page" >Reading</a> </li> <li> <a href="/en/library/Biology/2/Mendel-and-Inheritance/129/quiz">Quiz</a> </li> <li> <a href="/en/library/Biology/2/Mendel-and-Inheritance/129/resources">Teach with this</a> </li> </ul> </nav> </div> <script type="application/ld+json"> { "@context": "http://schema.org", "@type": "AudioObject", "contentUrl": "https://www.visionlearning.com/img/library/moduleAudio/module_129.mp3", "description": "Recording of Inheritance : Inheritance patterns have been of interest since ancient times, but it was Gregor Mendel's work in the mid-1800s that confirmed that traits are passed on by two parents in a predictable pattern. This module describes the experiments that resulted in <em>Mendel's Laws of Inheritance</em>. A look at specific traits in pea plants over generations shows how Mendel's research methods resulted in an understanding of dominant and recessive genes. Partial dominance is also discussed.", "encodingFormat": "mp3", "name": "module_129.mp3" } </script> <div class="module_header_audio"> <div class="audio-player border border-radius"> <audio id="audio"> <source src="https://www.visionlearning.com/img/library/moduleAudio/module_129.mp3" type="audio/mpeg"> Your browser does not support the audio element. </audio> <div class="audio-player__title"> <p>Listen to this reading</p> <span class="audio-player__timestamp" id="timestamp"> 00:00 </span> </div> <div class="audio-player__controls" id="controls"> <button class="button button--icon-only" id="play-pause-button"> <span class="icon icon-play" aria-hidden="true"></span> </button> <div class="audio-player__progress" id="progress-bar" tabindex="0" aria-valuemin="0" aria-valuemax="100" aria-valuenow="0" aria-label="Use arrow keys to forward or rewind the audio" role="slider"> <div class="audio-player__progress__fill"> <span class="audio-player__thumb"></span> </div> </div> <div class="audio-player__volume-container"> <button id="mute-button"> <span class="icon icon-volume"></span> </button> <div class="audio-player__volume" tabindex="0" aria-valuemin="0" aria-valuemax="100" aria-valuenow="100" aria-label="Use arrow keys to adjust volume" role="slider"> <div class="audio-player__volume__fill"> <span class="audio-player__thumb"></span> </div> </div> </div> </div> </div> </div> </header> <hr class="divider"/>   <div class="grid grid--sidebar-right grid--divider"> <div class="order-2 order-1--lg module__main"> <div class="narrow margin-x-auto margin-y-5"> <div class="accordion margin-bottom-5">  <button class="accordion__button" id="acc-button-key-concepts" data-accordion="button" aria-controls="acc-panel-key-concepts" aria-expanded="true" tabindex="0"> Did you know? </button> <div class="accordion__panel shown show" id="acc-panel-key-concepts" data-accordion="panel" aria-labelledby="acc-button-key-concepts" role="region"> <div class="accordion__panel__content"> <p>Did you know people used to believe that fully formed miniature versions of offspring were contained in sperm cells? Early theories of reproduction were later disproven, but inheritance patterns remained a mystery until Gregor Mendel performed his groundbreaking experiments with pea plants in the 1800s.</p> </div> </div>  <button class="accordion__button" id="acc-button-table-of-contents" data-accordion="button" aria-controls="acc-panel-table-of-contents" aria-expanded="false" tabindex="0"> Key concepts </button> <div class="accordion__panel" id="acc-panel-table-of-contents" data-accordion="panel" aria-labelledby="acc-button-table-of-contents" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <ul class="bulleted"><li><p>Mendel determined that an organism inherits two copies of the genetic material that determines an individual's physical traits, one copy coming from each the male and female parent.</p></li> <li><p>Mendel observed that for each trait, sometimes what is inherited from one parent masks what is inherited from the other. He called the hidden trait recessive and the expressed trait dominant.</p></li> <li><p>Since the time of Mendel, other scientists have observed that not all traits are inherited with the simple dominant-recessive pattern; incomplete dominance and co-dominance can result in a variety of phenotypes for some traits.</p></li></ul> </div> </div>  <button class="accordion__button" id="acc-button-terms-you-should-know" data-accordion="button" aria-controls="acc-panel-terms-you-should-know" aria-expanded="false" tabindex="0"> Terms you should know </button> <div class="accordion__panel" id="acc-panel-terms-you-should-know" data-accordion="panel" aria-labelledby="acc-button-terms-you-should-know" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <dl> <dt><a href="/en/glossary/view/breeding">breeding </a></dt> <dd> the production of offspring; the propagation of plants or animals by sexual means </dd> <dt><a href="/en/glossary/view/experiment">experiment </a></dt> <dd> a test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed </dd> <dt><a href="/en/glossary/view/generation">generation </a></dt> <dd> offspring at the same step in the line of descent from a common ancestor </dd> <dt><a href="/en/glossary/view/inheritance">inheritance </a></dt> <dd> the transmission of genetic traits from parent to offspring</dd> </dl> </div> </div> </div> <hr class="border-color-dark" /> <section> <div class="container narrow"> <p>Genetics might be one of the oldest scientific pursuits. The Bible tells of Jacob <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> only the goats and sheep with valued coat colors (Genesis 30:32-43), and it's generally believed that dogs were domesticated more than 20,000 years ago by mating wolves with tamer dispositions. However, genetics is also a young science since its founding father, <mark class="term" data-term="Gregor Mendel" data-term-def="Austrian Augustinian monk and scientist born in Heizendorf (now Hynice, Chech Republic) (1822-1884). In 1865, Mendel wrote <i>Versuche über Pflanzen-Hybride (Treatises&hellip;" data-term-url="/en/glossary/view/Mendel%2C+Gregor/4509">Gregor Mendel</mark>, performed his groundbreaking work less than 200 years ago. Mendel's work revealed two fundamental truths: that physical <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark> are determined by factors (now called genes) passed on by both <mark class="term" data-term="parent" data-term-def="The material or source from which something is derived." data-term-url="/en/glossary/view/parent/1618">parents</mark>, and that these factors are passed in a predictable pattern from one <mark class="term" data-term="generation" data-term-def="Offspring at the same step in the line of descent from a common ancestor." data-term-url="/en/glossary/view/generation/8293">generation</mark> to the next (Figure 1). Mendel's contributions are so profound that his ideas are often referred to as Mendel's <mark class="term" data-term="law" data-term-def="In science, a principle that describes a phenomenon, often mathematically." data-term-url="/en/glossary/view/law/8686">Laws</mark> of <mark class="term" data-term="inheritance" data-term-def="The transmission of genetic traits from parent to offspring." data-term-url="/en/glossary/view/inheritance/8294">Inheritance</mark>.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3222-050214020222.jpg" alt="Figure 1: Sheep are selectively bred for various qualities, including the color, length and texture of their coat, the abundance of their milk, or their general hardiness." /> </button> <figcaption> <p><b>Figure 1:</b> Sheep are selectively bred for various qualities, including the color, length and texture of their coat, the abundance of their milk, or their general hardiness.</p> </figcaption> </figure> </div> <p>If <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> patterns and <mark class="term" data-term="inheritance" data-term-def="The transmission of genetic traits from parent to offspring." data-term-url="/en/glossary/view/inheritance/8294">inheritance</mark> have been of interest since ancient times, why did it take until the mid-1800s to describe the <mark class="term" data-term="law" data-term-def="In science, a principle that describes a phenomenon, often mathematically." data-term-url="/en/glossary/view/law/8686">laws</mark> that govern them? What was so special about Mendel that motivated him to perform and understand the <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> as he did?</p> <p><section id="toc_1" class=""> <h2>Previous explanations of <mark class="term" data-term="inherited" data-term-def="Passed down from one generation to another generation." data-term-url="/en/glossary/view/inherited/8738">inherited</mark> characteristics</h2></p> <p>In Mendel's time, there were many explanations for how characteristics were <mark class="term" data-term="inherited" data-term-def="Passed down from one generation to another generation." data-term-url="/en/glossary/view/inherited/8738">inherited</mark>. Because offspring often appear related but not identical to their <mark class="term" data-term="parent" data-term-def="The material or source from which something is derived." data-term-url="/en/glossary/view/parent/1618">parents</mark>, one <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark> proposed that physical <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark> became blended in each new <mark class="term" data-term="generation" data-term-def="Offspring at the same step in the line of descent from a common ancestor." data-term-url="/en/glossary/view/generation/8293">generation</mark>, just as paints can be mixed to give new colors. However, even supporters of the "blending" theory had difficulty explaining how traits like blue eyes could reappear, unblended, in later generations.</p><p>Another popular <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark> in Mendel's time proposed that sperm <mark class="term" data-term="cell" data-term-def="The basic structural unit of all living things." data-term-url="/en/glossary/view/cell/8286">cells</mark> held a miniature but fully formed offspring and that the female's egg contributed an "essence," allowing the offspring to grow. This theory explained that pregnant females stopped menstruating because the blood was redirected into the growing fetus, but it could not satisfactorily describe the <mark class="term" data-term="evolution" data-term-def="Change in the gene pool of a population from generation to generation by such processes as mutation, natural selection, and genetic drift." data-term-url="/en/glossary/view/evolution/5284">evolution</mark> of new <mark class="term" data-term="species" data-term-def="1. In biological classifications, it is the lowest and most basic unit of the Linnaean taxonomic hierarchy (although it is also&hellip;" data-term-url="/en/glossary/view/species/893">species</mark> (Darwin's <em>Origin of Species</a></em> would not be published until 1859, when Mendel was already collecting <mark class="term" data-term="data" data-term-def="(plural form of <b>datum</b>) A collection of pieces of information, generally taking the form of numbers, text, bits, or facts, that&hellip;" data-term-url="/en/glossary/view/data/3729">data</mark> from his genetic <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark>. For more information, see our <a href="/en/library/Biology/2/Charles-Darwin-I/110">Charles Darwin I</a> module). The "miniature being" theory was debunked with improved <mark class="term" data-term="light" data-term-def="A form of electromagnetic radiation. Visible light is that associated with stimulating the organs of sight, which for normal human&hellip;" data-term-url="/en/glossary/view/light/1498">light</mark> microscopes of the 1830s when researchers could directly observe the subcellular world of plants and animals, and no <mark class="term" data-term="evidence" data-term-def="Support for an idea, opinion, or hypothesis." data-term-url="/en/glossary/view/evidence/8243">evidence</mark> for preformed offspring could be found.</p><p> A few years later, in 1859, <mark class="term" data-term="Louis Pasteur" data-term-def="A French chemist and biologist, born in Dole, France (1822-1895). Pasteur founded the science of microbiology and proved that microorganisms cause&hellip;" data-term-url="/en/glossary/view/Pasteur%2C+Louis/4468">Louis Pasteur</mark>'s <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> dispelled another popular idea referred to as <em>spontaneous generation</em>, which proposed that life arose from a special brew of non-living materials. In this era of failed and failing <mark class="term" data-term="theory" data-term-url="/en/glossary/view/theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;">theories</mark>, Mendel began his work.</p></section> <section id="toc_2"> <h2>Mendel's experiment</h2> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3247-050217120218.jpg" alt="Figure 2: The fruit-bearing pod of Pisum satvium, the common pea plant used by Gregor Mendel in his breeding experiments. " /> </button> <figcaption> <p><b>Figure 2:</b> The fruit-bearing pod of Pisum satvium, the common pea plant used by Gregor Mendel in his breeding experiments. </p> </figcaption> </figure> </div> <p>Gregor Johann Mendel was an Austrian monk who performed <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> in a monastery known for its scientific as well as its religious pursuits. Beginning in 1843, Mendel undertook experiments to understand the particulars of <mark class="term" data-term="heredity" data-term-def="The passing of genetic traits from parent to offspring." data-term-url="/en/glossary/view/heredity/8287">heredity</mark>, initially <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> normal and albino mice and then looking at the coat color of the offspring. Mendel's experiments with mice proved unsatisfactory since the mice took too long to breed and bore so few young in each litter. Additionally, they smelled terrible and some people felt animal breeding experiments were carnal and inappropriate work for a monk. Consequently, Mendel began looking at <mark class="term" data-term="inheritance" data-term-def="The transmission of genetic traits from parent to offspring." data-term-url="/en/glossary/view/inheritance/8294">inheritance</mark> in plants, using <em>Pisum stavium</em>, the formal name for simple garden peas (Figure 2). Many varieties of this plant existed, peas were inexpensive and could be grown in rows of pots in the monastery garden, and each plant gave Mendel many peas to examine.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3248-050223110223.jpg" alt="Figure 3: Pea flowers." /> </button> <figcaption> <p><strong>Figure 3:</strong> Pea flowers.</p> </figcaption> </figure> </div> <p>Breeding plants was different from <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> mice, but Mendel still had matchmaking work to perform. Flowering plants (Figure 3) have both male and female reproductive parts. The <mark class="term" data-term="pollen" data-term-def="Gamete of a flowering plant, similar to sperm cells in mammalian organisms." data-term-url="/en/glossary/view/pollen/3295">pollen</mark> of a flower, found on the flower's <mark class="term" data-term="anther" data-term-def="Male part of a flowering plant that holds pollen." data-term-url="/en/glossary/view/anther/3298">anthers</mark>, is similar to sperm <mark class="term" data-term="cell" data-term-def="The basic structural unit of all living things." data-term-url="/en/glossary/view/cell/8286">cells</mark> in other <mark class="term" data-term="organism" data-term-def="Any connected living system, such as an animal, plant, fungus, or bacterium. Organisms may be composed of a single cell or&hellip;" data-term-url="/en/glossary/view/organism/2171">organisms</mark>; and the flower's egg cells, called <mark class="term" data-term="ovule" data-term-def="Gamete of a flowering plant, similar to egg cells in mammalian organisms." data-term-url="/en/glossary/view/ovule/3296">ovules</mark>, are kept separate from the pollen by hiding them inside a compartment called the <mark class="term" data-term="carpel" data-term-def="(also called Pistil) Female part of a flowering plant consisting of ovary with ovules and stigma/stamen structures to receive pollen." data-term-url="/en/glossary/view/carpel/3297">carpel</mark>. Breezes or bugs can transfer pollen from the anthers of one flower and leave it on the carpel of another ("cross-pollination"). Just as easily, pollen can travel from the anthers to the carpel of the same flower, resulting in self-pollination. Using a paintbrush, Mendel played the part of a selective insect and pollinated particular plants by brushing the powder from the anthers of one variety onto the carpel of another. To avoid any self-pollination, Mendel also "emasculated" the recipient plants, using tweezers to snip off their anthers. Some might have thought that this, too, was odd work for a monk, but Mendel persisted.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3225-050214020235.jpg" alt="Figure 4: Two of the different phenotypes expressed by Pisum satvium." /> </button> <figcaption> <p><b>Figure 4:</b> Two of the different phenotypes expressed by Pisum satvium.</p> </figcaption> </figure> </div> <p>Mendel chose seven physical <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark> (now referred to as phenotypes) to study: flower color and placement, pod color and shape, pea color and shape, and plant size (Figure 4). These were all easily observable properties of the plants and so could be quickly counted. Mendel's goal was to reveal the genetic makeup (now called genotype) underlying each variety of pea plant and to understand how each trait was <mark class="term" data-term="inherited" data-term-def="Passed down from one generation to another generation." data-term-url="/en/glossary/view/inherited/8738">inherited</mark>. Performing his <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> took at least as much patience as skill. Mendel began by making "pure breeding" plants, ones that reliably gave rise to plants of the same physical traits <mark class="term" data-term="generation" data-term-def="Offspring at the same step in the line of descent from a common ancestor." data-term-url="/en/glossary/view/generation/8293">generation</mark> after generation. This alone took him two years but gave him confidence in the genetic makeup of his starting plants, which he called the <em>parental</em> generation of his experiment.</p><p>Using his paintbrush, Mendel's next step was to cross-pollinate parental plants with different physical <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark>, yielding offspring that were the <mark class="term" data-term="hybrid" data-term-def="Pertaining to the offspring of two plants or animals of different breeds, varieties, species, or genera. Hybrid often refers to plants&hellip;" data-term-url="/en/glossary/view/hybrid/5314">hybrid</mark> of two different plants. He recorded the appearance of each trait in the hybrid offspring plants, called the first <mark class="term" data-term="filial" data-term-def="In science, filial is commonly used to designate the sequence of generations following the parental generation. For example, the first filial&hellip;" data-term-url="/en/glossary/view/filial/4759">filial</mark> <mark class="term" data-term="generation" data-term-def="Offspring at the same step in the line of descent from a common ancestor." data-term-url="/en/glossary/view/generation/8293">generation</mark> (or F1 generation), and then followed the <mark class="term" data-term="inheritance" data-term-def="The transmission of genetic traits from parent to offspring." data-term-url="/en/glossary/view/inheritance/8294">inheritance</mark> pattern to the next generation by self-pollinating the F1 plants to produce the second filial generation (F2) and carefully recording each variety that arose. Mendel's mathematical approach to the question of inheritance is one of his greatest legacies. In genetics (as in other sciences) it is easy to be misled by the results of a few <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark>. Flip two coins and they may both show heads, but flip 1,000 coins and the split of heads to tails will be nearly even. In Mendel's case he examined more than 1,000 plants for their size and more than 8,000 peas for their color.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc6348"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">The observable physical traits of an organism are called</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6348-0-option-a" name="quiz-option-6348" type="radio" value="phenotypes." > <span class="option__label"> <span class="screen-reader-only">a.</span> phenotypes. </span> </label> <span class="quiz__response" id="response-6348-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6348-1-option-b" name="quiz-option-6348" type="radio" value="genotypes." > <span class="option__label"> <span class="screen-reader-only">b.</span> genotypes. </span> </label> <span class="quiz__response" id="response-6348-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_3"> <h2>Mendel's results</h2><p>The first physical <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">trait</mark> that Mendel studied extensively was pea shape. He had two pure <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> lines of plants: one that always gave rise to round peas and another that always gave wrinkled ones. He cross-pollinated these two parental lines and found that every F1 <mark class="term" data-term="hybrid" data-term-def="Pertaining to the offspring of two plants or animals of different breeds, varieties, species, or genera. Hybrid often refers to plants&hellip;" data-term-url="/en/glossary/view/hybrid/5314">hybrid</mark> plant had round peas. This may not have been entirely surprising since most varieties of pure breeding plants in Mendel's collection had round peas, so he might have guessed that the round character would dominate and the wrinkled character would recede into the background. Mendel showed that the result was the same whether the <mark class="term" data-term="pollen" data-term-def="Gamete of a flowering plant, similar to sperm cells in mammalian organisms." data-term-url="/en/glossary/view/pollen/3295">pollen</mark> from plants with round peas was used to <mark class="term" data-term="pollinate" data-term-def="To fertilize (in plants). Plants may be self-pollinating, or may need a pollinator to transfer pollen to the stigma, thus fertilizing&hellip;" data-term-url="/en/glossary/view/pollinate/5273">pollinate</mark> plants with wrinkled peas, or the other way around. The consistent results from such "reciprocal crosses" led Mendel to the conclusion that is now called <b>Mendel's First Law</b>: Factors that determine physical traits segregate into <em>both</em> egg and sperm <mark class="term" data-term="cell" data-term-def="The basic structural unit of all living things." data-term-url="/en/glossary/view/cell/8286">cells</mark> (collectively called the "gametes" of the organism). Unlike earlier <mark class="term" data-term="theory" data-term-url="/en/glossary/view/theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;">theories</mark> that suggested only sperm carried traits, Mendel showed that both egg and sperm carry physical traits to the offspring.</p><p>Mendel's next <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiment</mark> was particularly telling. He self-pollinated each F1 <mark class="term" data-term="hybrid" data-term-def="Pertaining to the offspring of two plants or animals of different breeds, varieties, species, or genera. Hybrid often refers to plants&hellip;" data-term-url="/en/glossary/view/hybrid/5314">hybrid</mark> plant with its own <mark class="term" data-term="pollen" data-term-def="Gamete of a flowering plant, similar to sperm cells in mammalian organisms." data-term-url="/en/glossary/view/pollen/3295">pollen</mark> and recorded the pea shape of the next (F2) <mark class="term" data-term="generation" data-term-def="Offspring at the same step in the line of descent from a common ancestor." data-term-url="/en/glossary/view/generation/8293">generation</mark>. Despite all the F1 plants having round peas, some F2 plants had round peas and some had wrinkled peas. In other words, <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark> that had been hidden in the F1 hybrids had reappeared in their offspring. Mendel counted each variety in the F2 generation and observed that 5,474 had round peas and 1,850 had wrinkled ones (Figure 5). The <mark class="term" data-term="ratio" data-term-def="The relationship between two or more quantities; relative amounts of two or more values expressed as a proportion." data-term-url="/en/glossary/view/ratio/8556">ratio</mark> of these two traits, very nearly three round peas for each wrinkled one, turned out to be an important number. Later, when Mendel repeated his experiments looking at pea color rather than shape, he found 6,022 yellow peas and 2,001 green peas in his F2 plants, again a ratio of 3:1. This 3:1 ratio held true in experiments examining flower color, flower position, pod shape, pod color, and plant size. What could explain this <mark class="term" data-term="constant" data-term-def="In mathematics, a quantity that has a fixed value; something that does not vary." data-term-url="/en/glossary/view/constant/8557">constant</mark> ratio? One of the strengths of Mendel's work is a hallmark of the scientific process: He put together his <mark class="term" data-term="observation" data-term-def="1. The act of noticing something. 2. A record of that which has been noticed." data-term-url="/en/glossary/view/observation/8255">observations</mark> to form a <mark class="term" data-term="hypothesis" data-term-def="From the Greek word <em>hypothesis</em> meaning assumption or the basis of an argument, a hypothesis is a proposal intended to explain&hellip;" data-term-url="/en/glossary/view/hypothesis/3727">hypothesis</mark>.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3250-050223110241.jpg" alt="Figure 5: Wrinkled peas, a phenotype that appeared approximately 1/4th of the time in the F2 generation of Mendel's experiments. " /> </button> <figcaption> <p><b>Figure 5:</b> Wrinkled peas, a phenotype that appeared approximately 1/4th of the time in the F2 generation of Mendel's experiments. </p> </figcaption> </figure> </div> <p>Three <mark class="term" data-term="observation" data-term-def="1. The act of noticing something. 2. A record of that which has been noticed." data-term-url="/en/glossary/view/observation/8255">observations</mark> led Mendel to his second important proposal. First, Mendel had observed that both the egg and sperm carry factors to the offspring. Second, he had shown that one <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">trait</mark> dominates in the initial cross of mixed <mark class="term" data-term="hybrid" data-term-def="Pertaining to the offspring of two plants or animals of different breeds, varieties, species, or genera. Hybrid often refers to plants&hellip;" data-term-url="/en/glossary/view/hybrid/5314">hybrids</mark> (for example, round peas in the F1 generation). Lastly, he had observed that a trait that recedes into the background in the F1 <mark class="term" data-term="generation" data-term-def="Offspring at the same step in the line of descent from a common ancestor." data-term-url="/en/glossary/view/generation/8293">generation</mark> reappears one-fourth of the time in the F2 generation. Working over the mathematics, Mendel realized that both <mark class="term" data-term="parent" data-term-def="The material or source from which something is derived." data-term-url="/en/glossary/view/parent/1618">parents</mark> carry two copies of each factor and that each parent must donate one copy to the offspring through their egg or sperm <mark class="term" data-term="cell" data-term-def="The basic structural unit of all living things." data-term-url="/en/glossary/view/cell/8286">cell</mark>. Since all of the offspring in the first cross (F1) carry one factor that dominates (round peas) and one factor that recedes (wrinkled), they all have round peas. However, their offspring (F2) could inherit either a round or wrinkled factor from each the egg and sperm. Only those F2 plants that inherit a wrinkled factor from both the egg and sperm had wrinkled peas – exactly a one-fourth <mark class="term" data-term="ratio" data-term-def="The relationship between two or more quantities; relative amounts of two or more values expressed as a proportion." data-term-url="/en/glossary/view/ratio/8556">ratio</mark>. Thus Mendel concluded that two factors must be involved in producing a physical trait; however, only one factor is passed on from parent to offspring in the sperm or egg cell. At the time, Mendel could not explain how the pairs separated into the <mark class="term" data-term="gamete" data-term-def="A reproductive cell having half the number of chromosomes (a haploid) of a mature cell, e.g., a sperm or egg cell." data-term-url="/en/glossary/view/gamete/3301">gametes</mark>, or how they rejoined during pollination, but he was correct in thinking that the factors randomly and independently segregated into the plant's gametes, and his idea is now called <b>Mendel's Second Law</b>.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc6349"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">When Mendel crossed two pure breeding lines of pea plants, one with round peas and one with wrinkled peas, the next generation produced round peas</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6349-0-option-a" name="quiz-option-6349" type="radio" value="only when the pollen from plants with round peas was used to pollinate plants with wrinkled peas." > <span class="option__label"> <span class="screen-reader-only">a.</span> only when the pollen from plants with round peas was used to pollinate plants with wrinkled peas. </span> </label> <span class="quiz__response" id="response-6349-0"> <strong>Incorrect.</strong> </span> </div> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6349-1-option-b" name="quiz-option-6349" type="radio" value="whether the pollen from plants with round peas was used to pollinate plants with wrinkled peas, or the other way around." > <span class="option__label"> <span class="screen-reader-only">b.</span> whether the pollen from plants with round peas was used to pollinate plants with wrinkled peas, or the other way around. </span> </label> <span class="quiz__response" id="response-6349-1"> <strong>Correct!</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_4"> <h2>Mendel's notation system</h2><p>Mendel devised a notation <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">system</mark> to follow the <mark class="term" data-term="inheritance" data-term-def="The transmission of genetic traits from parent to offspring." data-term-url="/en/glossary/view/inheritance/8294">inheritance</mark> of each <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">trait</mark>. As an example, consider Mendel's <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiment</mark> with plants that were tall (6 feet) or short (6 inches). Mendel had reasoned that each parental plant had a pair of factors that separated during reproduction and that the F1 offspring <mark class="term" data-term="inherited" data-term-def="Passed down from one generation to another generation." data-term-url="/en/glossary/view/inherited/8738">inherited</mark> one factor from each <mark class="term" data-term="parent" data-term-def="The material or source from which something is derived." data-term-url="/en/glossary/view/parent/1618">parent</mark>. Mendel called the pure <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> ("homozygous") parental plants "TT" if they grew tall (i.e., the <mark class="term" data-term="homozygous" data-term-def="Having two identical alleles for a given gene." data-term-url="/en/glossary/view/homozygous/5312">homozygous</mark> <mark class="term" data-term="dominant" data-term-def="Designating a genetic trait that is expressed when an organism has inherited two different variations (alleles) of a gene for that&hellip;" data-term-url="/en/glossary/view/dominant/8736">dominant</mark> genotype)or "tt" if short (i.e., the homozygous <mark class="term" data-term="recessive" data-term-def="Designating a genetic trait that is hidden when an organism has inherited two different variations (alleles) of a gene for that&hellip;" data-term-url="/en/glossary/view/recessive/8737">recessive</mark> genotype). He could have named the short plants "SS," but instead he used uppercase letters for the trait that dominated in the F1 <mark class="term" data-term="generation" data-term-def="Offspring at the same step in the line of descent from a common ancestor." data-term-url="/en/glossary/view/generation/8293">generation</mark> and used the same letter, but lowercase, to describe the recessive trait (the one that disappeared in the F1 generation but reappeared in the F2 generation). Cross-pollinating the TT and tt plants gave <mark class="term" data-term="hybrid" data-term-def="Pertaining to the offspring of two plants or animals of different breeds, varieties, species, or genera. Hybrid often refers to plants&hellip;" data-term-url="/en/glossary/view/hybrid/5314">hybrids</mark> with a mixed (heterozygous) <mark class="term" data-term="genotype" data-term-def="The genetic makeup of an organism or group of organisms; the genetic description of an individual. Genotype may refer to a&hellip;" data-term-url="/en/glossary/view/genotype/3300">genotype</mark> ("Tt"). These hybrids all showed the dominant trait and grew tall.</p><p>In his next <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiment</mark> Mendel self-pollinated plants of the Tt <mark class="term" data-term="genotype" data-term-def="The genetic makeup of an organism or group of organisms; the genetic description of an individual. Genotype may refer to a&hellip;" data-term-url="/en/glossary/view/genotype/3300">genotype</mark> and saw both tall and short plants arise. Mendel correctly concluded that the tall plants had either received two <mark class="term" data-term="dominant" data-term-def="Designating a genetic trait that is expressed when an organism has inherited two different variations (alleles) of a gene for that&hellip;" data-term-url="/en/glossary/view/dominant/8736">dominant</mark> factors ("TT" like the original pure <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> plants), or one dominant and one <mark class="term" data-term="recessive" data-term-def="Designating a genetic trait that is hidden when an organism has inherited two different variations (alleles) of a gene for that&hellip;" data-term-url="/en/glossary/view/recessive/8737">recessive</mark> factor ("Tt" like the F1 generation). However, the short plants must have <mark class="term" data-term="inherited" data-term-def="Passed down from one generation to another generation." data-term-url="/en/glossary/view/inherited/8738">inherited</mark> two recessive versions of the factor and were once again <mark class="term" data-term="homozygous" data-term-def="Having two identical alleles for a given gene." data-term-url="/en/glossary/view/homozygous/5312">homozygous</mark> "tt." Mendel's insight into the genotype of his plants was remarkable given that nothing was known about the physical nature of inherited material. Mendel's "factors" are now known to be <mark class="term" data-term="gene" data-term-def="Material (usually DNA) that is inherited from a parent and which encodes for a cellular component important for some cellular function." data-term-url="/en/glossary/view/gene/3294">genes</mark> encoded by <mark class="term" data-term="DNA" data-term-def="Deoxyribonucleic acid. A double-stranded nucleic acid containing the sugar 2-deoxy-D-ribose. A constituent of cellular nuclear material responsible for encoding&hellip;" data-term-url="/en/glossary/view/DNA/1604">DNA</mark>, and the variations are called <mark class="term" data-term="allele" data-term-def="A variation of a genetic element, usually resulting in a distinct trait." data-term-url="/en/glossary/view/allele/3302">alleles</mark>. "T" and "t" are alleles of one genetic factor, the one that determines plant size.</p><p>If both the "TT" and "Tt" <mark class="term" data-term="genotype" data-term-def="The genetic makeup of an organism or group of organisms; the genetic description of an individual. Genotype may refer to a&hellip;" data-term-url="/en/glossary/view/genotype/3300">genotypes</mark> give rise to tall plants and only the "tt" genotype gives short plants, shouldn't Mendel have seen two tall plants to every one short? A Punnett square like the one shown shown in Figure 6 is a useful way to calculate products from genetic crosses and can be used here to understand the 3:1 <mark class="term" data-term="ratio" data-term-def="The relationship between two or more quantities; relative amounts of two or more values expressed as a proportion." data-term-url="/en/glossary/view/ratio/8556">ratio</mark> that Mendel saw. Continuing the tall and short plant example, the "TT" and "tt" <mark class="term" data-term="gamete" data-term-def="A reproductive cell having half the number of chromosomes (a haploid) of a mature cell, e.g., a sperm or egg cell." data-term-url="/en/glossary/view/gamete/3301">gametes</mark> from each pure <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> plant can be written across the top or along the left side of a four-quadrant box. Within the box, the individual factors are "donated" to the F1 <mark class="term" data-term="progeny" data-term-def="The descendant or offspring of an organism." data-term-url="/en/glossary/view/progeny/5320">progeny</mark>, resulting in a "Tt" genotype in all four quadrants. All these plants would (and did!) grow tall.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3220-050208030211.jpg" alt="Figure 6: Punnett square showing a parental cross of a two plants, one with alleles TT and the other with alleles tt. All offspring (F1) are tT, possessing the recessive short gene, and expressing the dominant tall gene." /> </button> <figcaption> <p><b>Figure 6:</b> Punnett square showing a parental cross of a two plants, one with alleles TT and the other with alleles tt. All offspring (F1) are tT, possessing the recessive short gene, and expressing the dominant tall gene.</p> </figcaption> </figure> </div> <p>A Punnett square for crosses of the F1 plants shows a different <mark class="term" data-term="outcome" data-term-def="Result." data-term-url="/en/glossary/view/outcome/8247">outcome</mark>. Both sides of the Punnett square in Figure 7 have "T" and "t" to represent the two possible <mark class="term" data-term="gamete" data-term-def="A reproductive cell having half the number of chromosomes (a haploid) of a mature cell, e.g., a sperm or egg cell." data-term-url="/en/glossary/view/gamete/3301">gametes</mark> from each <mark class="term" data-term="heterozygous" data-term-def="Having two different alleles for a given gene." data-term-url="/en/glossary/view/heterozygous/5313">heterozygous</mark> plant. The <mark class="term" data-term="genotype" data-term-def="The genetic makeup of an organism or group of organisms; the genetic description of an individual. Genotype may refer to a&hellip;" data-term-url="/en/glossary/view/genotype/3300">genotypes</mark> of the offspring are written inside the square at the intersections: "tT," "tt," "TT," and "Tt." Thus, the 3:1 <mark class="term" data-term="ratio" data-term-def="The relationship between two or more quantities; relative amounts of two or more values expressed as a proportion." data-term-url="/en/glossary/view/ratio/8556">ratio</mark> that Mendel observed can be understood by realizing that three intersections have one or more <mark class="term" data-term="dominant" data-term-def="Designating a genetic trait that is expressed when an organism has inherited two different variations (alleles) of a gene for that&hellip;" data-term-url="/en/glossary/view/dominant/8736">dominant</mark> factor (it doesn't matter if it's listed first or second in the Punnett square), and thus all three result in tall plants, and only one square has both <mark class="term" data-term="recessive" data-term-def="Designating a genetic trait that is hidden when an organism has inherited two different variations (alleles) of a gene for that&hellip;" data-term-url="/en/glossary/view/recessive/8737">recessive</mark> factors (tt), resulting in short plants.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3221-050208030256.jpg" alt="Figure 7: Punnett square showing the F1 cross of two plants with alleles Tt. As Mendel observed, 3/4ths of the offspring possess at least one copy of the dominant tall gene, while 1/4th of the offspring possess two copies of the short gene." /> </button> <figcaption> <p><b>Figure 7:</b> Punnett square showing the F1 cross of two plants with alleles Tt. As Mendel observed, 3/4ths of the offspring possess at least one copy of the dominant tall gene, while 1/4th of the offspring possess two copies of the short gene.</p> </figcaption> </figure> </div> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc6358"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">A tall plant of the Tt genotype has</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6358-0-option-a" name="quiz-option-6358" type="radio" value="two dominant factors for height." > <span class="option__label"> <span class="screen-reader-only">a.</span> two dominant factors for height. </span> </label> <span class="quiz__response" id="response-6358-0"> <strong>Incorrect.</strong> </span> </div> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6358-1-option-b" name="quiz-option-6358" type="radio" value="one dominant factor and one recessive factor for height." > <span class="option__label"> <span class="screen-reader-only">b.</span> one dominant factor and one recessive factor for height. </span> </label> <span class="quiz__response" id="response-6358-1"> <strong>Correct!</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_5"> <h2>Mendel's laws: Violations and variations</h2><p>The monastery had many varieties of pea plants to study, and perhaps it was luck or perhaps it was intuition, but all seven of the <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark> Mendel chose to study are <mark class="term" data-term="inherited" data-term-def="Passed down from one generation to another generation." data-term-url="/en/glossary/view/inherited/8738">inherited</mark> in a straightforward pattern. The relationship of <mark class="term" data-term="DNA" data-term-def="Deoxyribonucleic acid. A double-stranded nucleic acid containing the sugar 2-deoxy-D-ribose. A constituent of cellular nuclear material responsible for encoding&hellip;" data-term-url="/en/glossary/view/DNA/1604">DNA</mark> and <mark class="term" data-term="chromosome" data-term-def="The organized genetic structure of DNA with associated proteins that contains the hereditary information necessary for reproduction, protein manufacture, and other functions." data-term-url="/en/glossary/view/chromosome/3760">chromosomes</mark> to <mark class="term" data-term="heredity" data-term-def="The passing of genetic traits from parent to offspring." data-term-url="/en/glossary/view/heredity/8287">heredity</mark> was not known in Mendel's time. Modern <mark class="term" data-term="analysis" data-term-def="The careful study of data to look for patterns." data-term-url="/en/glossary/view/analysis/8553">analysis</mark> has since shown that five of the seven traits that Mendel studied are encoded by <mark class="term" data-term="gene" data-term-def="Material (usually DNA) that is inherited from a parent and which encodes for a cellular component important for some cellular function." data-term-url="/en/glossary/view/gene/3294">genes</mark> on distinct chromosomes of the pea plant, and the remaining two are at opposite ends of one chromosome and so are separated by lots of other genes. Had Mendel examined two traits encoded by neighboring genes, he would have observed what <mark class="term" data-term="Thomas Hunt Morgan" data-term-def="(September 25, 1866 - December 4, 1945) An American embryologist who won the Nobel Prize in Physiology or Medicine in 1933&hellip;" data-term-url="/en/glossary/view/Morgan%2C+Thomas+Hunt/5316">Thomas Hunt Morgan</mark> found in the early twentieth century from his <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> with fruit flies. Genes that are close to each other (called "linked" genes) have different <mark class="term" data-term="inheritance" data-term-def="The transmission of genetic traits from parent to offspring." data-term-url="/en/glossary/view/inheritance/8294">inheritance</mark> patterns than the unlinked genes that Mendel studied.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3228-050216120240.jpg" alt="Figure 8: Snapdragons, shown here, have incomplete dominance in flower color, unlike peas. A cross of a plant with red flowers with a plant with white flowers results in plants with pink flowers. " /> </button> <figcaption> <p><b>Figure 8:</b> Snapdragons, shown here, have incomplete dominance in flower color, unlike peas. A cross of a plant with red flowers with a plant with white flowers results in plants with pink flowers. </p> </figcaption> </figure> </div> <p>It was also Mendel's good fortune (or perhaps his genius) to study quantifiable <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark> determined by only one pair of <mark class="term" data-term="gene" data-term-def="Material (usually DNA) that is inherited from a parent and which encodes for a cellular component important for some cellular function." data-term-url="/en/glossary/view/gene/3294">genes</mark>. Pea plants were either tall or short, their peas either green or yellow. There was nothing in between; many genes are now known to show "incomplete dominance," and there are numerous <mark class="term" data-term="phenotype" data-term-def="The appearance of an organism resulting from the interaction of the genotype and the environment. Simply, what physical traits the organism expresses." data-term-url="/en/glossary/view/phenotype/3299">phenotypes</mark> (physical traits) that arise from the combined action of many genes. For example, some plants show incomplete dominance in flower color; when pure varieties that have either red (RR) flowers or white (rr) flowers are bred, the <mark class="term" data-term="hybrid" data-term-def="Pertaining to the offspring of two plants or animals of different breeds, varieties, species, or genera. Hybrid often refers to plants&hellip;" data-term-url="/en/glossary/view/hybrid/5314">hybrid</mark> (Rr) offspring have flowers that are pink (Figure 8).<p><p>Mendel studied this phenomenon using a bean plant called <em>P. multiflorus</em> and noted that the <mark class="term" data-term="outcome" data-term-def="Result." data-term-url="/en/glossary/view/outcome/8247">outcome</mark> did not confirm the 3:1 <mark class="term" data-term="ratio" data-term-def="The relationship between two or more quantities; relative amounts of two or more values expressed as a proportion." data-term-url="/en/glossary/view/ratio/8556">ratio</mark> he had seen with the flower color of his pea plants. Mendel corresponded with many colleagues, and one of these, <mark class="term" data-term="Carl Nageli" data-term-def="(aka Karl Wilhelm von Nägeli) Swiss botanist who studied cell division and pollination (1817 - 1891). Nageli was a prolific&hellip;" data-term-url="/en/glossary/view/Nageli%2C+Carl/5311">Carl Nageli</mark>, a Professor of Botany at the University in Munich, sent Mendel some hawkweed seeds to study. But this plant has an unusual mode of reproduction in which some of the <mark class="term" data-term="maternal" data-term-def="Derived from or related to one's mother." data-term-url="/en/glossary/view/maternal/5315">maternal</mark> tissue is reused in the offspring, and so the crosses of the pure <mark class="term" data-term="breeding" data-term-def="The production of offspring; the propagation of plants or animals by sexual means." data-term-url="/en/glossary/view/breeding/8291">breeding</mark> plants did not show the expected 3:1 ratio. Mendel was reportedly discouraged by this and wondered if his "laws of inheritance" were universal.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid129/Image/VLObject-3223-050214020225.jpg" alt="Figure 9: The coat color of a Siamese cat like the one shown here is determined by both genetic and environmental factors. " /> </button> <figcaption> <p><b>Figure 9:</b> The coat color of a Siamese cat like the one shown here is determined by both genetic and environmental factors. </p> </figcaption> </figure> </div> <p>Fur color on animals is another good example of a complex <mark class="term" data-term="phenotype" data-term-def="The appearance of an organism resulting from the interaction of the genotype and the environment. Simply, what physical traits the organism expresses." data-term-url="/en/glossary/view/phenotype/3299">phenotype</mark>. In labrador retrievers, fur color is determined by two <mark class="term" data-term="gene" data-term-def="Material (usually DNA) that is inherited from a parent and which encodes for a cellular component important for some cellular function." data-term-url="/en/glossary/view/gene/3294">gene</mark> pairs. One pair colors the fur brown or black, and another pair gives rise to a yellow coat. Coat color on Siamese cats is even more complex, being influenced by environmental factors as well as genes so that it grows darker around the nose, tail, and paws of these cats where their bodies are colder (Figure 9). For mice, determination of fur color is more complicated, with five gene pairs involved. Fortunately, Mendel abandoned his <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> with mice early and did not pursue any complex <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark> like these for his experiments.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc6357"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">A cross of a snapdragon plant with red flowers with another with white flowers results in plants with pink flowers due to</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6357-0-option-a" name="quiz-option-6357" type="radio" value="incomplete dominance." > <span class="option__label"> <span class="screen-reader-only">a.</span> incomplete dominance. </span> </label> <span class="quiz__response" id="response-6357-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6357-1-option-b" name="quiz-option-6357" type="radio" value="a pure genotype." > <span class="option__label"> <span class="screen-reader-only">b.</span> a pure genotype. </span> </label> <span class="quiz__response" id="response-6357-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_6"> <h2>Mendel presents his findings</h2><p>Mendel presented his major findings in a two-part lecture in 1865 followed by a paper entitled "Experiments on Plant Hybridization" in 1866. Unlike the furor created a few years earlier by Darwin's publication, Mendel's proposals were essentially ignored, their truth unrecognized for years, even though the prevalent notions of <mark class="term" data-term="inheritance" data-term-def="The transmission of genetic traits from parent to offspring." data-term-url="/en/glossary/view/inheritance/8294">inheritance</mark> were clearly insufficient and the intellectual room to accept his ideas was available.</p><p>Mendel did what he could to generate interest in his findings by sending reprints of his article to other people studying <mark class="term" data-term="inheritance" data-term-def="The transmission of genetic traits from parent to offspring." data-term-url="/en/glossary/view/inheritance/8294">inheritance</mark>, but to his disappointment, Mendel never enjoyed wide readership or even a common understanding of his work in his lifetime. Today, no one disputes the significance of Mendel's contribution, although some have argued that his insights arose more from luck than from genius. Whatever the balance of intellect and fortune, Mendel's impact on modern thought is unquantifiable, unlike the inheritance of <mark class="term" data-term="trait" data-term-def="A specific characteristic that is genetically determined." data-term-url="/en/glossary/view/trait/8271">traits</mark> he studied.</p> </div> </section> <hr class="border-color-dark" /> <footer class="module__footer"> <p class="citation"> <em> Natalie H. Kuldell “Inheritance” Visionlearning Vol. BIO (7), 2005. </em> </p>  <div class="title-list" name="further"> <p class="h6 title-list__title"> Further Reading </p> <ul class="grid grid--column-2--md grid--column-3--md gap-1"> <li> <a class="no-hover-focus height-100" href="/en/library/Biology/2/Mendel-and-Independent-Assortment/145"> <article class="flex-row align-items-center flex-column--md align-items-start--md height-100 theme-light padding-2 gap-2"> <div class="width-30 width-auto--md"> <img class="border-radius box-shadow-1" src="/img/library/moduleImages/featured_image_145-23061209063608.jpg" alt="Independent Assortment"> </div> <div class="flex-grow-shrink"> <h2 class="h6 font-weight-normal"> Independent Assortment: <em>Mendel's testcrosses and Punnett squares</em> </h2> </div> </article> </a> </li> </ul> </div> </footer> </div>   </div>  <div class="order-1 order-2--lg module__tools"> <div class="narrow margin-x-auto position-sticky-top font-size-md"> <div class="padding-2 border-radius box-shadow-1--lg"> <div class="tabs" role="tablist"> <nav> <button class="button button--icon-label" id="tab-button-in-this-module" aria-label="Table of Contents" aria-controls="tab-panel-module__tools" aria-selected="true" role="tab"> <span class="icon icon-list" aria-hidden="true"></span> <span class="button__text">Contents</span> </button> <button class="button button--icon-label" id="tab-button-toggle-terms" aria-controls="tab-panel-toggle-terms" aria-selected="false" role="tab"> <span class="icon icon-glossary-highlight"></span> <span class="button__text">Glossary Terms</span> </button> </nav> <hr class="divider" /> <div class="tabs__panel shown" id="tab-panel-module__tools" aria-labelledby="tab-button-module__tools" role="tabpanel"> <p class="font-weight-bold margin-bottom-1"> Table of Contents </p> <div class="table-of-contents" id="module-toc"> <ul> <li><a href="/en/library/Biology/2/Mendel-and-Inheritance/129#toc_1">Previous explanations of inherited characteristics</a> </li> <li><a href="/en/library/Biology/2/Mendel-and-Inheritance/129#toc_2">Mendel's experiment</a> </li> <li><a href="/en/library/Biology/2/Mendel-and-Inheritance/129#toc_3">Mendel's results</a> </li> <li><a href="/en/library/Biology/2/Mendel-and-Inheritance/129#toc_4">Mendel's notation system</a> </li> <li><a href="/en/library/Biology/2/Mendel-and-Inheritance/129#toc_5">Mendel's laws: Violations and variations</a> </li> <li><a href="/en/library/Biology/2/Mendel-and-Inheritance/129#toc_6">Mendel presents his findings</a> </li> </ul> </div> </div>   <div class="tabs__panel" id="tab-panel-toggle-terms" aria-labelledby="tab-button-toggle-terms" role="tabpanel"> <div class="reading-toggle"> <div class="reading-toggle__switch"> <div class="form-entry__option__switch"> <label> <input type="checkbox" name="termsToggleSwitch" id="terms-toggle-switch" /> <span class="switch__slider"></span> <span class="option__label text-decoration-none font-size-md"> Highlight Glossary Terms </span> </label> </div> </div> <div class="reading-toggle__help"> <p> <em> Activate glossary term highlighting to easily identify key terms within the module. 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