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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Genes get shuffled when chromosomes exchange pieces :: DNA from the Beginning</title> <meta name="description" content="Linkage groups on chromosomes gave clues to where genes are located." /> <link rel="preload" as="style" src="/css/main.css"> <link rel="preload" as="script" src="/js/swfobject.js"> <link rel="preload" as="script" src="/js/prototype-1.6.1.js"> <link href="/css/main.css" rel="stylesheet" type="text/css" /> <link href='https://fonts.googleapis.com/css?family=Droid+Serif' rel='stylesheet' type='text/css'/> <link href='https://fonts.googleapis.com/css?family=Droid+Sans' rel='stylesheet' type='text/css'/> <script type="text/javascript" src="/js/swfobject.js"></script> <script type="text/javascript" src="/js/prototype-1.6.1.js"></script> </head> <body> <div id="container"> <div id="content"> <div id="header"> <div class="rollover-home"> <a href="/" class="rollover-home" title="DNA from the Beginning Home"><span class="displace">Home</span></a> </div> </div>  <div id="content-container"> <h1><span> Concept 11</span> Genes get shuffled when chromosomes exchange pieces.</h1> <div id="nav"> <ul> <li class="menu1"><a href="index.html" title="CONCEPT" ><span class="displace">CONCEPT</span></a></li> <li class="menu2"><a href="animation.html" title="ANIMATION"><span class="displace">ANIMATION</span></a></li> <li class="menu3"><a href="gallery.html" title="GALLERY"><span class="displace">GALLERY</span></a></li> <li class="menu4"><a href="av.html" title="VIDEO"><span class="displace">VIDEO</span></a></li> <li class="menu5"><a href="bio.html" title="BIO"><span class="displace">BIO</span></a></li> <li class="menu6"><a href="problem.html" title="PROBLEM"><span class="displace">PROBLEM</span></a></li> <li class="menu7"><a href="links.html" title="LINKS" ><span class="displace">LINKS</span></a></li> </ul> <br class="clearfloat" /> </div> <div id="concept"> <img src="/images/11/concept11.jpg" class="concept-image" alt="Genes get shuffled when chromosomes exchange pieces." /> <p>As Morgan and his coworkers identified more and more inherited traits in fruit flies, they noticed that flies often showed particular combinations of traits. This suggested that certain genes were "linked," and inherited together as a unit. They identified four such units or "linkage groups" — equal to the number of paired chromosomes observed under the microscope. This provided further evidence that genes are located on chromosomes.</p> <p>Morgan's group used the phenomenon of linkage to construct maps of the fruit fly chromosomes. They found that linked genes are sometimes separated during meiosis, when the homologous chromosomes exchange pieces. How often a pair of genes are separated provides a measure of the relative distance between them on a chromosome. Distant genes recombine frequently. Nearby genes rarely recombine and are closely linked. </p> </div> </div> <br class="clearfloat" /> <div id="footer"> <ul> <li><a href="/">Home</a></li> <li><a href="/sitemap.html">Site Map</a></li> <li><a href="/scientists.html">Scientists</a></li> <li><a href="/glossary.html">Glossary</a></li> <li><a href="/feedback.html">Feedback</a></li> <li><a href="/awards.html">Awards</a></li> <li><a href="/credits.html">Credits</a></li> <li><a href="http://blogs.dnalc.org/dnaftb/" style="background-image:none;">Blog</a></li> </ul> <p> Funded by <a href="http://macyfoundation.org">The Josiah Macy, Jr. Foundation</a><br /> © 2002 - 2011, <a href="http://www.dnalc.org/"> DNA Learning Center</a>, <a href="https://www.cshl.edu/">Cold Spring Harbor Laboratory</a>. All rights reserved. </p> </div>  </div> <div id="sidebar"> <div id="search" > <form method="get" action="/search"> <div class="fieldHolder1"> <input type="search" id="q" name="q" placeholder="Search" onclick="this.value=''" value="" /> <img style="background-color:#9C0;" src="/images/general/search_icon.jpg" alt="Search" onclick="document.forms[0].submit()" /> </div> </form> </div>  <div id="sidebar"> <ul class="sections-side sections-side1a" style="padding-top: 56px; margin-top: 3px;"> <li ><a href="/1/"><img src="/images/thumbnails/1-thumb-sm.png" alt="1." />Children resemble their parents.</a></li> <li ><a href="/2/"><img src="/images/thumbnails/2-thumb-sm.png" alt="2." />Genes come in pairs.</a></li> <li ><a href="/3/"><img src="/images/thumbnails/3-thumb-sm.png" alt="3." />Genes don't blend.</a></li> <li ><a href="/4/"><img src="/images/thumbnails/4-thumb-sm.png" alt="4." />Some genes are dominant.</a></li> <li ><a href="/5/"><img src="/images/thumbnails/5-thumb-sm.png" alt="5." />Genetic inheritance follows rules.</a></li> <li ><a href="/6/"><img src="/images/thumbnails/6-thumb-sm.png" alt="6." />Genes are real things.</a></li> <li ><a href="/7/"><img src="/images/thumbnails/7-thumb-sm.png" alt="7." />All cells arise from pre-existing cells.</a></li> <li ><a href="/8/"><img src="/images/thumbnails/8-thumb-sm.png" alt="8." />Sex cells have one set of chromosomes; body cells have two.</a></li> <li ><a href="/9/"><img src="/images/thumbnails/9-thumb-sm.png" alt="9." />Specialized chromosomes determine sex.</a></li> <li ><a href="/10/"><img src="/images/thumbnails/10-thumb-sm.png" alt="10." />Chromosomes carry genes.</a></li> <li ><a class="concept-highlight" href="/11/"><img src="/images/thumbnails/11-thumb-sm.png" alt="11." />Genes get shuffled when chromosomes exchange pieces.</a></li> <li ><a href="/12/"><img src="/images/thumbnails/12-thumb-sm.png" alt="12." />Evolution begins with the inheritance of gene variations.</a></li> <li ><a href="/13/"><img src="/images/thumbnails/13-thumb-sm.png" alt="13." />Mendelian laws apply to human beings.</a></li> <li style="border-bottom: 1px solid #669;"><a href="/14/"><img src="/images/thumbnails/14-thumb-sm.png" alt="14." />Mendelian genetics cannot fully explain human health and behavior.</a></li> </ul> <ul class="menu-side"> <li class="section2"><a href="/15/index.html" title="Molecules of Genetics"><span class="displace">MOLECULES OF GENETICS</span></a></li> <li class="section3" ><a href="/29/index.html" title="Genetic Organization and Control"><span class="displace">GENETIC ORGANIZATION AND CONTROL</span></a></li> </ul> </div> </div>  <br class="clearfloat" /> </div>  <script type="text/javascript"> Event.observe(window, 'load', function() { var uri = '/11/index.html'; uri = uri.replace(/-\d/,''); $('nav').down().descendants().each(function(s) { if (s.nodeName == 'A') { if (s.href.match(uri)) { s.addClassName('current'); throw $break; } } }); }); </script> <script type="text/javascript"> var _gaq = _gaq || []; _gaq.push(['_setAccount', 'UA-1818773-10']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = 'https://www.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); </script>  <script async src="https://www.googletagmanager.com/gtag/js?id=G-K6EHFCRJBP"></script> <script> window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', 'G-K6EHFCRJBP'); </script> </body> </html>