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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>DNA and proteins are key molecules of the cell nucleus :: DNA from the Beginning</title> <meta name="description" content="DNA and protein are candidates for transmitting hereditary information." /> <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 15</span> DNA and proteins are key molecules of the cell nucleus.</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/15/concept15.jpg" class="concept-image" alt="DNA and proteins are key molecules of the cell nucleus." /> <p>DNA was discovered as a major chemical of the nucleus at about the same time Mendel and Darwin published their work. However, during the early 1900s, proteins were considered better candidates as molecules able to transmit large amounts of hereditary information from generation to generation.</p> <p>Although DNA was known to be a very large molecule, it seemed likely that its four chemical components were assembled in a monotonous pattern — like a synthetic polymer. Also, no specific cellular function had yet been found for DNA. Proteins, on the other hand, were important as enzymes and structural components of living cells. Proteins were also known to be polymers of numerous amino acids. These polymers are called polypeptides. Most importantly, the 20 amino acid "alphabet" of proteins potentially could be configured into more unique information-carrying structures than the four-letter alphabet of DNA. </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="menu-side"> <li class="section1" style="margin-bottom: 3px;"><a href="/1/index.html" title="Classical Genetics"><span class="displace">CLASSICAL GENETICS</span></a></li> </ul> <ul class="sections-side sections-side2a" style="padding-top: 56px;"> <li ><a class="concept-highlight" href="/15/"><img src="/images/thumbnails/15-thumb-sm.png" alt="15." />DNA and proteins are key molecules of the cell nucleus.</a></li> <li ><a href="/16/"><img src="/images/thumbnails/16-thumb-sm.png" alt="16." />One gene makes one protein.</a></li> <li ><a href="/17/"><img src="/images/thumbnails/17-thumb-sm.png" alt="17." />A gene is made of DNA.</a></li> <li ><a href="/18/"><img src="/images/thumbnails/18-thumb-sm.png" alt="18." />Bacteria and viruses have DNA too.</a></li> <li ><a href="/19/"><img src="/images/thumbnails/19-thumb-sm.png" alt="19." />The DNA molecule is shaped like a twisted ladder.</a></li> <li ><a href="/20/"><img src="/images/thumbnails/20-thumb-sm.png" alt="20." />A half DNA ladder is a template for copying the whole.</a></li> <li ><a href="/21/"><img src="/images/thumbnails/21-thumb-sm.png" alt="21." />RNA is an intermediary between DNA and protein.</a></li> <li ><a href="/22/"><img src="/images/thumbnails/22-thumb-sm.png" alt="22." />DNA words are three letters long.</a></li> <li ><a href="/23/"><img src="/images/thumbnails/23-thumb-sm.png" alt="23." />A gene is a discrete sequence of DNA nucleotides.</a></li> <li ><a href="/24/"><img src="/images/thumbnails/24-thumb-sm.png" alt="24." />The RNA message is sometimes edited.</a></li> <li ><a href="/25/"><img src="/images/thumbnails/25-thumb-sm.png" alt="25." />Some viruses store genetic information in RNA.</a></li> <li ><a href="/26/"><img src="/images/thumbnails/26-thumb-sm.png" alt="26." />RNA was the first genetic molecule.</a></li> <li ><a href="/27/"><img src="/images/thumbnails/27-thumb-sm.png" alt="27." />Mutations are changes in genetic information.</a></li> <li style="border-bottom: 1px solid #669;"><a href="/28/"><img src="/images/thumbnails/28-thumb-sm.png" alt="28." />Some types of mutations are automatically repaired.</a></li> </ul> <ul class="menu-side"> <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 = '/15/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>