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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>Explore Britten's DNA reassociation rates for different organisms :: DNA from the Beginning</title> <meta name="description" content="Problem in Concept 31: Some DNA does not encode protein, DNA from the Beginning." /> <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 31</span> Some DNA does not encode protein.</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="problem"> <div id="animation-holder"> <div id="animation-container"></div> <script type="text/javascript"> (function() { //var server = 'http://content.dnalc.org/'; var server = ''; var isCanvasSupported = function(){ var elem = document.createElement('canvas'); return !!(elem.getContext && elem.getContext('2d')); }; var preloadLinkCC = document.createElement("link"); //preloadLinkCC.href = 'https://code.createjs.com/createjs-2015.11.26.min.js'; preloadLinkCC.href = '/content/_createjs/createjs-2015.11.26.min.js'; preloadLinkCC.rel = 'preload'; preloadLinkCC.as = 'script'; document.head.appendChild(preloadLinkCC); var preloadLink = document.createElement("link"); preloadLink.href = server + '/content/c16/16666/con31pro_Canvas.html'; preloadLink.rel = 'preload'; preloadLink.as = 'document'; document.head.appendChild(preloadLink); var load_DNAFTB_animation = function(container, uri) { var newIFrame = document.createElement('iframe'); newIFrame.setAttribute('src', uri); newIFrame.setAttribute('width', '780px'); newIFrame.setAttribute('height', '377px'); newIFrame.setAttribute('scrolling', 'no'); //newIFrame.setAttribute('sandbox', 'allow-scripts'); newIFrame.setAttribute('frameborder', '0'); container.appendChild(newIFrame); }; load_DNAFTB_animation(document.querySelector("#animation-container"), server + '/content/c16/16666/con31pro_Canvas.html'); })(); </script> <canvas style="height:1px; width:780px;">HI! Britten脙垄芒聜卢芒聞垄s Cot curve analysis compares DNA complexity. A useful number in this type of analysis is Cot1/2. This is the value when 50% of the DNA has reassociated. For example, the Cot1/2 of E. coli is 9. What is the approximate Cot1/2 of bacteriophage T4 DNA? 9 (No, this is the Cot1/2 of E. coli.) 1 (No, this is not correct.) 10 (No, this is close to the Cot1/2 of E. coli.) 10 -1 (That is correct) The Cot1/2 of T4 DNA is 3 X 10-1. The Cot1/2 value is derived from the log of the DNA concentration X time. A greater Cot1/2 value means a slower reaction. It takes longer for E. coli DNA to completely reassociate than bacteriophage T4. The Cot1/2 value is also related to the amount of DNA present in the genome 脙垄芒聜卢芒聙聺 the concentration of complementary sequences. A larger genome has more DNA, but by comparing Cot1/2 values with E. coli, the "complexity" of a genome can be calculated. The complexity is the total length of different sequences present in a genome and is usually expressed in base pairs. The E. coli genome has only unique sequences; the total length of different sequences is 4.2 X 106bp. What is the complexity of bacteriophage T4 DNA? 4.2 X 10 6 bp (No, this is the size of the E. coli genome.) 4.2 X 10 5bp (No, this is not correct.) 1.4 X 10 6 bp (No, this is not correct.) 1.4 X 10 5 bp (That is correct) Bacteriophage T4 has a Cot1/2 of 3 X 10 -1, and the Cot1/2 of E. coli is 9. The complexity of the bacteriophage T4 genome is 1.4 X 10 5bp. Now, let脙垄芒聜卢芒聞垄s look at eukaryotic DNA. Since there are three components to this reassociation curve, each component has its own Cot1/2value. What are the Cot1/2values of the fast, medium and slow components? 0.004, 3, 1000 (That is correct) 10, 10, 10 (No, the Cot1/2 values aren脙垄芒聜卢芒聞垄t all the same.) 0.004, 10, 1000 (No, one of the values is incorrect.) 1, 10, 1000 (No, two of the values are incorrect.) The Cot1/2values of the fast, medium and slow components of this curve are 0.004, 3 and 1000. The fast component of this curve represents 25% of the total DNA, the medium component is 30% and the slow component is 45%. If we could isolate these fractions and run them as separate reassociation reactions, then the Cot1/2values would be: 0.004, 3, 1000 (No, these are the original Cot values. 0.25, 0.3, 0.45 (No, these are the % DNA in each component.) 1 X 10 -3, 0.9, 450 (That is correct) If we treat each of the components as separate reactions, then the Cot1/2values for the fast, medium and slow curves would be 1 X 10 -3, 0.9, 450. What is the complexity of the slow fraction of this eukaryotic DNA? 1.47 X 10 8 bp. (No, that is not correct.) 4.7 X 10 8 bp. (That is correct) 5.95 X 10 8 bp. (No, that is not correct.) 6.62 X 10 8 bp. (No, that is not correct.) Since you are comparing the Cot1/2value of 45% of the eukaryotic DNA, the E. coli Cot1/2 value needs to be factored for 45%. This means that:450 / (9 X 0.45) = complexity of the slow fraction / 4.2 X 10 6= 4.7 X 10 8. The complexity of the slow fraction is the total length of unique sequence in this genome. Since the slow fraction is only 45% of the DNA, what is the estimated size of the whole genome? 4.7 x 10 8 bp. (No, this is not correct) 1.47 x 10 8 bp. (No, this is not correct) 1.0 x 10 9 bp. (That is correct) If 4.7 X 10 8 bp represents 45% of the genome, then 1.0 X 10 9 bp represents 100% of the genome. CONGRATULATIONS!!! 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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="menu-side" > <li class="section1"><a href="/1/index.html" title="Classical Genetics"><span class="displace">CLASSICAL GENETICS</span></a></li> <li class="section2" style="margin-bottom: 3px;"><a href="/15/index.html" title="Molecules of Genetics"><span class="displace">MOLECULES OF GENETICS</span></a></li>  </ul> <ul class="sections-side sections-side3a" style="padding-top: 56px;" > <li ><a href="/29/"><img src="/images/thumbnails/29-thumb-sm.png" alt="29." />DNA is packaged in a chromosome.</a></li> <li ><a href="/30/"><img src="/images/thumbnails/30-thumb-sm.png" alt="30." />Higher cells incorporate an ancient chromosome.</a></li> <li ><a class="concept-highlight" href="/31/"><img src="/images/thumbnails/31-thumb-sm.png" alt="31." />Some DNA does not encode protein.</a></li> <li ><a href="/32/"><img src="/images/thumbnails/32-thumb-sm.png" alt="32." />Some DNA can jump.</a></li> <li ><a href="/33/"><img src="/images/thumbnails/33-thumb-sm.png" alt="33." />Genes can be turned on and off.</a></li> <li ><a href="/34/"><img src="/images/thumbnails/34-thumb-sm.png" alt="34." />Genes can be moved between species.</a></li> <li ><a href="/35/"><img src="/images/thumbnails/35-thumb-sm.png" alt="35." />DNA responds to signals from outside the cell.</a></li> <li ><a href="/36/"><img src="/images/thumbnails/36-thumb-sm.png" alt="36." />Different genes are active in different kinds of cells.</a></li> <li ><a href="/37/"><img src="/images/thumbnails/37-thumb-sm.png" alt="37." />Master genes control basic body plans.</a></li> <li ><a href="/38/"><img src="/images/thumbnails/38-thumb-sm.png" alt="38." />Development balances cell growth and death.</a></li> <li ><a href="/39/"><img src="/images/thumbnails/39-thumb-sm.png" alt="39." />A genome is an entire set of genes.</a></li> <li ><a href="/40/"><img src="/images/thumbnails/40-thumb-sm.png" alt="40." />Living things share common genes.</a></li> <li style="border-bottom: 1px solid #669;"><a href="/41/"><img src="/images/thumbnails/41-thumb-sm.png" alt="41." />DNA is only the beginning for understanding the human genome.</a></li> </ul> </div>  </div>  <br class="clearfloat" /> </div>  <script type="text/javascript"> Event.observe(window, 'load', function() { var uri = '/31/problem.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>