publicdata/nih-gov
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
nih-gov/medlineplus.gov/genetics/understanding/basics/dna/index.html
Scott Williams 7bcb500d37 Initial commit.
2025-02-26 13:17:41 -05:00

492 lines
26 KiB
HTML
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<!DOCTYPE html>
<html lang="en" id="understanding_genetics" class="nojs us" data-root="https://medlineplus.gov/">
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
<meta http-equiv="window-target" content="_top" />
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link rel="canonical" href="https://medlineplus.gov/genetics/understanding/basics/dna/" />
<link rel="alternate" hreflang="en" href="https://medlineplus.gov/genetics/understanding/basics/dna/" />
<link rel="alternate" hreflang="es" href="https://medlineplus.gov/spanish/genetica/entender/basica/adn/" />
<meta name="ac-dictionary" content="medlineplus-ac-dictionary" />
<meta name="description" content="DNA is the hereditary material in humans and almost all other organisms. Genes are made up of DNA. " />
<link rel="shortcut icon" href="https://medlineplus.gov/images/favicon.ico" type="image/x-icon" />
<link rel="apple-touch-icon" href="https://medlineplus.gov/images/touch-icon.png" />
<meta property="fb:app_id" content="1042245625821448" />
<meta property="og:title" content="What is DNA?: MedlinePlus Genetics" />
<meta property="og:url" content="https://medlineplus.gov/genetics/understanding/basics/dna/" />
<meta property="og:image" content="https://medlineplus.gov/images/CellsAndDNA_Share.jpg" />
<meta property="og:description" content="DNA is the hereditary material in humans and almost all other organisms. Genes are made up of DNA. " />
<meta name="twitter:card" content="summary_large_image" />
<meta name="twitter:site" content="@medlineplus" />
<meta name="twitter:creator" content="@medlineplus" />
<meta name="twitter:title" content="What is DNA?: MedlinePlus Genetics" />
<meta name="twitter:description" content="DNA is the hereditary material in humans and almost all other organisms. Genes are made up of DNA. " />
<meta name="twitter:image" content="https://medlineplus.gov/images/CellsAndDNA_Share.jpg" />
<meta name="twitter:image:alt" content=""/>
<meta property="og:image:alt" content="" />
<title>What is DNA?: MedlinePlus Genetics</title>
<link rel="stylesheet" href="https://medlineplus.gov/css/common_new.css?1738957188506" />
<!--[if IE 8]> <link rel="stylesheet" href="https://medlineplus.gov/css/ie8/common.css"> <![endif]-->
<link rel="stylesheet" href="https://medlineplus.gov/uswds/css/uswds_styles.css" />
<link rel="stylesheet" href="https://medlineplus.gov/utilities/lostatic.css">
<script type="text/javascript">document.getElementsByTagName('html')[0].className = document.getElementsByTagName('html')[0].className.replace( /(?:^|\s)nojs(?!\S)/g , '').trim();</script>
<script src="https://medlineplus.gov/uswds/js/uswds-init.min.js" type="text/javascript"></script>
<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','GTM-MMVM77');</script>
</head>
<body>
<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-MMVM77"
height="0" width="0" style="display:none;visibility:hidden" title="googletagmanager"></iframe></noscript>
<a name="top" id="top"></a>
<a class="hide-offscreen" href="#start">Skip navigation</a>
<section
class="usa-banner"
aria-label="Official website of the United States government"
>
<div class="usa-accordion">
<header class="usa-banner__header">
<div class="usa-banner__inner">
<div class="grid-col-auto">
<img
aria-hidden="true"
class="usa-banner__header-flag"
src="https://medlineplus.gov/uswds/img/us_flag_small.png"
alt=""
/>
</div>
<div class="grid-col-fill tablet:grid-col-auto" aria-hidden="true">
<p class="usa-banner__header-text">
An official website of the United States government
</p>
<p class="usa-banner__header-action">Here’s how you know</p>
</div>
<button
type="button"
class="usa-accordion__button usa-banner__button"
aria-expanded="false"
aria-controls="gov-banner-default-default"
>
<span class="usa-banner__button-text">Here’s how you know</span>
</button>
</div>
</header>
<div
class="usa-banner__content usa-accordion__content"
id="gov-banner-default-default"
>
<div class="grid-row grid-gap-lg">
<div class="usa-banner__guidance tablet:grid-col-6">
<img
class="usa-banner__icon usa-media-block__img"
src="https://medlineplus.gov/uswds/img/icon-dot-gov.svg"
role="img"
alt=""
aria-hidden="true"
/>
<div class="usa-media-block__body">
<p>
<strong>Official websites use .gov</strong><br />A
<strong>.gov</strong> website belongs to an official government
organization in the United States.
</p>
</div>
</div>
<div class="usa-banner__guidance tablet:grid-col-6">
<img
class="usa-banner__icon usa-media-block__img"
src="https://medlineplus.gov/uswds/img/icon-https.svg"
role="img"
alt=""
aria-hidden="true"
/>
<div class="usa-media-block__body">
<p>
<strong>Secure .gov websites use HTTPS</strong><br />A
<strong>lock</strong> (
<span class="icon-lock"
><svg
xmlns="http://www.w3.org/2000/svg"
width="52"
height="64"
viewBox="0 0 52 64"
class="usa-banner__lock-image"
role="img"
aria-labelledby="banner-lock-description-default"
focusable="false"
>
<title id="banner-lock-title-default">Lock</title>
<desc id="banner-lock-description-default">Locked padlock icon</desc>
<path
fill="#000000"
fill-rule="evenodd"
d="M26 0c10.493 0 19 8.507 19 19v9h3a4 4 0 0 1 4 4v28a4 4 0 0 1-4 4H4a4 4 0 0 1-4-4V32a4 4 0 0 1 4-4h3v-9C7 8.507 15.507 0 26 0zm0 8c-5.979 0-10.843 4.77-10.996 10.712L15 19v9h22v-9c0-6.075-4.925-11-11-11z"
/>
</svg> </span
>) or <strong>https://</strong> means you’ve safely connected to
the .gov website. Share sensitive information only on official,
secure websites.
</p>
</div>
</div>
</div>
</div>
</div>
</section>
<div id="mplus-wrap">
<header>
<div id="mplus-header">
<div id="mplus-orgs">
<a href="https://www.nih.gov/" class="nih-org" target="_blank" title="National Institutes of Health">
<img class="nihlogo" src="https://medlineplus.gov/images/nihlogo.png" alt="National Institutes of Health"/>
</a><a href="https://www.nlm.nih.gov/" target="_blank"> National Library of Medicine</a>
</div>
<div id="mplus-logo" class="years-25">
<a href="https://medlineplus.gov/">
<img alt="MedlinePlus Trusted Health Information for You" title="MedlinePlus Trusted Health Information for You" src="https://medlineplus.gov/images/m_logo_25.png"/>
</a>
</div>
<div id="mplus-nav">
<div aria-live="polite" class="sm-live-area hide-offscreen"></div>
<button id="sm-menu-btn" class="navmenu-btn" title="Menu" role="button" aria-controls="mplus-menu-list" type="submit">Menu<span class="icon icon-nav-menu"></span></button>
<ul id="mplus-menu-list" class="nav-list">
<li><a href="https://medlineplus.gov/healthtopics.html">Health Topics</a></li>
<li><a href="https://medlineplus.gov/druginformation.html">Drugs & Supplements</a></li>
<li><a href="https://medlineplus.gov/genetics/">Genetics</a></li>
<li><a href="https://medlineplus.gov/lab-tests/">Medical Tests</a></li>
<li><a href="https://medlineplus.gov/encyclopedia.html">Medical Encyclopedia</a></li>
<li><a href="https://medlineplus.gov/about/">About MedlinePlus</a></li>
</ul><button id="sm-search-btn" class="navmenu-btn" title="Search" role="button" aria-controls="mplus-search" type="submit"><span class="hide-offscreen"></span>Search<span class="icon icon-nav-search"></span></button>
<div class="top-1">
<form id="mplus-search" method="get" action="https://vsearch.nlm.nih.gov/vivisimo/cgi-bin/query-meta" title="Search MedlinePlus" target="_self">
<input type="hidden" name="v:project" value="medlineplus"/>
<input type="hidden" name="v:sources" value="medlineplus-bundle"/>
<div class="form-box text-combo">
<div class="form-area"><label class="hide-offscreen" for="searchtext_primary">Search MedlinePlus</label>
<input id="searchtext_primary" class="form-text" type="text" placeholder="Search MedlinePlus" alt="#Site Search input" title="Site Search input" maxlength="400" size="40" name="query" autocomplete="off" role="textbox" aria-autocomplete="list" aria-haspopup="true"/>
</div>
<div class="button-area">
<button class="form-btn" title="Search MedlinePlus" alt="Search MedlinePlus" type="submit">GO</button>
</div>
</div>
</form>
<div class="secondarynav">
<ul class="nav-list">
<li><a href="https://medlineplus.gov/about/"><span>About MedlinePlus</span></a></li>
<li><a href="https://medlineplus.gov/whatsnew/">What's New</a></li>
<li><a href="https://medlineplus.gov/sitemap.html"><span>Site Map</span></a></li>
<li><a href="https://support.nlm.nih.gov/knowledgebase/category/?id=CAT-01231&category=medlineplus&from=https%3A//medlineplus.gov/genetics/understanding/basics/dna/" target="_blank"><span>Customer Support</span></a></li>
</ul>
</div>
</div>
<div id="mplus-nav-bar">
<ul class="nav-list">
<li><a href="https://medlineplus.gov/healthtopics.html">Health Topics</a></li><li><a href="https://medlineplus.gov/druginformation.html">Drugs & Supplements</a></li><li><a href="https://medlineplus.gov/genetics/">Genetics</a></li><li><a href="https://medlineplus.gov/lab-tests/">Medical Tests</a></li><li><a href="https://medlineplus.gov/encyclopedia.html">Medical Encyclopedia</a></li>
</ul>
</div>
<a id="mplus-lang-toggle" href="https://medlineplus.gov/spanish/genetica/entender/basica/adn/" title="Español">Español</a>
</div>
</div>
</header>
<div id="mplus-content">
<div id="breadcrumbs">
<div itemprop="breadcrumb" itemscope="" itemtype="http://schema.org/BreadcrumbList">
<span class="hide-offscreen">You Are Here:</span>
<div itemscope itemprop="itemListElement" itemtype="http://schema.org/ListItem">
<a href="https://medlineplus.gov/" itemprop="item"><span itemprop="name">Home</span></a>
&rarr;
<meta itemprop="position" content="1"/>
</div>
<div itemscope itemprop="itemListElement" itemtype="http://schema.org/ListItem">
<a href="https://medlineplus.gov/genetics/" itemprop="item"><span itemprop="name">Genetics</span></a>
&rarr;
<meta itemprop="position" content="2"/>
</div>
<div itemscope itemprop="itemListElement" itemtype="http://schema.org/ListItem">
<a href="https://medlineplus.gov/genetics/understanding/" itemprop="item"><span itemprop="name">Help Me Understand Genetics</span></a>
&rarr;
<meta itemprop="position" content="3"/>
</div>
<div itemscope itemprop="itemListElement" itemtype="http://schema.org/ListItem">
<a href="https://medlineplus.gov/genetics/understanding/basics/" itemprop="item"><span itemprop="name">Cells and DNA</span></a>
&rarr;
<meta itemprop="position" content="4"/>
</div>
<div>
<span>What is DNA?</span>
</div>
</div>
</div>
<span class="page-url print-only">URL of this page: https://medlineplus.gov/genetics/understanding/basics/dna/</span>
<div >
<article>
<div class="page-info">
<div class="page-title">
<a name="start" id="start"></a>
<h1>What is DNA?</h1>
</div>
<div class="page-actions"></div>
<noscript><span class="js-disabled-message">To use the sharing features on this page, please enable JavaScript.</span></noscript>
</div>
<div class="main">
<section><div class="mp-content"><p>DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called <a data-pid="20079" href="https://medlineplus.gov/genetics/chromosome/mitochondrial-dna/">mitochondrial DNA</a> or mtDNA). <a class="image-modal" data-alt="Mitochondria are structures within the cell cytoplasm." data-caption="" data-credit="U.S. National Library of Medicine" data-filepath="images/PX00004O_PRESENTATION.jpeg" data-imgtype="genetics" data-pix="PX00004O" data-sourceurl="" data-title="Mitochondria" href="https://medlineplus.gov/images/PX00004O_PRESENTATION.jpeg" id="PX00004O_2" title="Show image">Mitochondria<img alt="" aria-hidden="true" class="image-modal-icon" src="https://medlineplus.gov/css/img/icon_camera_small.png"/></a> are structures within cells that convert the energy from food into a form that cells can use.</p>
<p>The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.</p>
<p>DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.</p>
<p>An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.</p>
<div class="mediaobject">
<div class="caption">
<p>DNA is a double helix formed by base pairs attached to a sugar-phosphate backbone.</p>
</div>
<div class="imagedata"><img alt="DNA is made up of base pairs and a sugar phosphate backbone." height="400" src="https://medlineplus.gov/images/PX000098_PRESENTATION.jpeg" width="400"/></div>
<div class="image-credit">Credit: U.S. National Library of Medicine</div>
</div></div>
</section>
</div>
<div class="side">
<aside>
<section><div class="side-section"><div class="mp-content"><div class="section-header long-header">
<h2>For more information about DNA:</h2>
</div>
<div class="section-body">
<p>The National Human Genome Research Institute (NHGRI), a part of the National Institutes of Health (NIH), provides a fact sheet <a href="https://www.genome.gov/about-genomics/fact-sheets/Deoxyribonucleic-Acid-Fact-Sheet" target="_blank">Deoxyribonucleic Acid (DNA)</a> that gives an introduction to this molecule.<span class="desc-text"><img alt="From the National Institutes of Health" class="imgdesc" height="16" src="https://medlineplus.gov/images/nih.png" title="From the National Institutes of Health" width="25"/></span></p>
<p>StatedClearly offers <a href="https://www.statedclearly.com/videos/what-is-dna/" target="_blank">a video introduction to DNA and how it works</a>.</p>
<p>The New Genetics, a publication of the National Institute of General Medical Sciences, part of the NIH, discusses <a href="https://www.nigms.nih.gov/education/Booklets/the-new-genetics/Pages/Home.aspx" target="_blank">the structure of DNA and how it was discovered</a>.<span class="desc-text"><img alt="From the National Institutes of Health" class="imgdesc" height="16" src="https://medlineplus.gov/images/nih.png" title="From the National Institutes of Health" width="25"/></span></p>
<p>
<a href="https://askabiologist.asu.edu/dna-shape-and-structure" target="_blank">A basic explanation and illustration of DNA</a> can be found on Arizona State University's "Ask a Biologist" website.</p>
<p>The Virtual Genetics Education Centre, created by the University of Leicester, offers additional information on <a href="https://le.ac.uk/vgec/topics/dna/dna-higher-education" target="_blank">DNA, genes, and chromosomes</a>.</p>
<p>An <a href="https://neuromuscular.wustl.edu/mitosyn.html#general" target="_blank">overview of mitochondrial DNA</a> is available from the Neuromuscular Disease Center at Washington University in St. Louis.</p>
</div></div>
</div></section>
</aside>
</div>
<div class="bottom">
<section><div class="mp-exp mp-content"><h2>Topics in the Cells and DNA chapter</h2><ul><li><a data-pid="20105" href="https://medlineplus.gov/genetics/understanding/basics/cell/">What is a cell?</a></li><li>What is DNA?</li><li><a data-pid="20109" href="https://medlineplus.gov/genetics/understanding/basics/gene/">What is a gene?</a></li><li><a data-pid="20111" href="https://medlineplus.gov/genetics/understanding/basics/chromosome/">What is a chromosome?</a></li><li><a data-pid="20113" href="https://medlineplus.gov/genetics/understanding/basics/howmanychromosomes/">How many chromosomes do people have?</a></li><li><a data-pid="20115" href="https://medlineplus.gov/genetics/understanding/basics/noncodingdna/">What is noncoding DNA?</a></li></ul><p><a data-pid="20081" href="https://medlineplus.gov/genetics/understanding/">Other chapters in Help Me Understand Genetics</a></p></div>
</section>
<section>
<!--
<div class="from-ghr">
<img src="https://medlineplus.gov/images/fromGHR.png" alt="From Genetics Home Reference" />
<p>Genetics Home Reference has merged with MedlinePlus. Genetics Home Reference content now can be found in the "Genetics" section of MedlinePlus. <a href="https://medlineplus.gov/about/general/genetics/newhome/">Learn more</a></p>
</div>
-->
<p>The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.</p>
</section>
</div>
</article>
</div>
<div id="citation-how-to">
<button><span>Learn how to cite this page</span></button>
</div>
</div>
<footer>
<div id="mplus-footer">
<div class="footer1">
<ul class="secondarynav">
<li><a href="https://medlineplus.gov/about/">About MedlinePlus</a></li>
<li><a href="https://medlineplus.gov/whatsnew/">What's New</a></li>
<li><a href="https://medlineplus.gov/sitemap.html">Site Map</a></li>
<li><a href="https://support.nlm.nih.gov/knowledgebase/category/?id=CAT-01231&category=medlineplus&from=https%3A//medlineplus.gov/genetics/understanding/basics/dna/" target="_blank"><span>Customer Support</span></a></li>
</ul>
<ul class="follow-footer">
<li>
<a href="https://medlineplus.gov/rss.html" class="follow-item">Subscribe to RSS<img src="https://medlineplus.gov/images/feed.png" class="social-media-toolkit-icon" alt="RSS" title="RSS"></a>
</li>
<li>
<span class="follow-label">Follow us</span>
<a href="https://twitter.com/medlineplus" class="follow-item" target="_blank">
<img src="https://medlineplus.gov/images/i_share_twitter.png" class="follow-icon" alt="X" title="X">
</a>
<a href="https://facebook.com/Mplus.gov/" class="follow-item" target="_blank">
<img src="https://medlineplus.gov/images/i_share_fb.png" class="follow-icon" alt="Facebook" title="Facebook">
</a>
<a href="https://www.instagram.com/mplusgov/" class="follow-item" target="_blank">
<img src="https://medlineplus.gov/images/Instagram_Glyph_Gradient_RGB.png" class="follow-icon" alt="Instagram" title="Instagram">
</a>
</li>
<li>
<a href="https://medlineplus.gov/social-media-toolkit/" class="social-media-toolkit-item">Social Media Toolkit<img src="https://medlineplus.gov/images/i_social_media_toolkit.png" class="social-media-toolkit-icon" alt="Social Media Toolkit" title="Social Media Toolkit"></a>
</li>
</ul>
</div>
<div class="footer2">
<ul>
<li><a href=" https://www.nlm.nih.gov/web_policies.html" target='_blank'>NLM Web Policies</a></li>
<li><a href="https://medlineplus.gov/about/using/usingcontent/" >Copyright</a></li>
<li><a href="https://medlineplus.gov/accessibility.html">Accessibility</a></li>
<li><a href="https://medlineplus.gov/about/using/criteria/">Guidelines for Links</a></li>
<li><a href="https://medlineplus.gov/plugins.html">Viewers & Players</a></li>
<li><a href="https://www.hhs.gov/vulnerability-disclosure-policy/index.html" target="_blank">HHS Vulnerability Disclosure</a></li>
<li><a href="https://medlineplus.gov/medlineplus-connect/">MedlinePlus Connect for EHRs</a></li>
<li><a href="https://medlineplus.gov/about/developers/">For Developers</a></li>
</ul>
<div class="address">
<a href="https://www.nlm.nih.gov" target="_blank">National Library of Medicine</a>
<span>8600 Rockville Pike, Bethesda, MD 20894</span>
<a href="https://www.hhs.gov" target="_blank">U.S. Department of Health and Human Services</a>
<a href="https://www.nih.gov" target="_blank">National Institutes of Health</a>
</div>
<div class="date">
<span id="lastupdate">Last updated January 19, 2021</span>
</div>
<div class="return-top"><a href="#top" title="Return to top"><img class="return-top-icon" alt="Return to top" src="https://medlineplus.gov/images/return-top.png"></a></div>
</div>
</div>
</footer>
</div>
<script src="https://medlineplus.gov/jslib/jquery-3.6.0.min.js" type="text/javascript"></script>
<script src="https://medlineplus.gov/jslib/mplus-frontend-controls-new.js" type="text/javascript"></script>
<script src="https://medlineplus.gov/jslib/mplus-share.js?id=1112022" type="text/javascript"></script>
<!--[if lte IE 9]><script src="//www.nlm.nih.gov/medlineplus/jslib/jquery.placeholder.js" type="text/javascript"></script><![endif]-->
<script src="https://medlineplus.gov/jslib/control.js" type="text/javascript"></script>
<script src="https://medlineplus.gov/uswds/js/uswds.min.js" type="text/javascript"></script>
</body>
</html>
Reference in a new issue View git blame Copy permalink