CINXE.COM

<!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>Bacteria and viruses have DNA too :: DNA from the Beginning</title> <meta name="description" content="Bacterial conjugation and bacteriophages provide proof that a gene is made of DNA." /> <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 18</span> Bacteria and viruses have DNA too.</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/18/concept18.jpg" class="concept-image" alt="Bacteria and viruses have DNA too." /> <p>Microscopes proved the existence of single-celledbacteria. However, there was debate about whether bacteria had genes and what attributes they may have in common with higher life forms. This debate was settled in the 1940's, when it was discovered that bacteria have sex. During the process of conjugation, genes are exchanged through a mating channel that links two bacteria. </p> <p> Electron microscopy suggested that bacterial viruses carry on a similar process. A virus attaches to a host bacterium and injects its genes through its channel-like tail. In 1952, Alfred Hershey showed that DNA, alone, is responsible for the reproduction of new viruses within an infected cell. This provided undeniable support for Avery's earlier experiments that a gene is made of DNA. It also showed that viruses, as well as bacteria, can be used as models for studying universal principles of genetics.</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 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 class="concept-highlight" 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 = '/18/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>