{"id":264771,"date":"2025-07-21T16:08:25","date_gmt":"2025-07-21T16:08:25","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=264771"},"modified":"2025-07-21T16:08:28","modified_gmt":"2025-07-21T16:08:28","slug":"assume-that-a-100-base-pair-dna-double-helix-contains-45-cytosines","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/21\/assume-that-a-100-base-pair-dna-double-helix-contains-45-cytosines\/","title":{"rendered":"Assume that a 100-base pair DNA double helix contains 45 cytosines"},"content":{"rendered":"\n<p>Assume that a 100-base pair DNA double helix contains 45 cytosines. How many adenines are there?<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-6-color\">The correct answer and explanation is:<\/mark><\/strong><\/p>\n\n\n\n<p>In a DNA double helix, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). According to Chargaff&#8217;s rules, the amount of adenine equals the amount of thymine, and the amount of cytosine equals the amount of guanine in a given DNA molecule.<\/p>\n\n\n\n<p>Given that the DNA molecule is 100 base pairs long and contains 45 cytosines, this means that there are also 45 guanines (since C pairs with G). The remaining base pairs must be adenine-thymine pairs. Since there are 100 base pairs in total, we subtract the 45 cytosines and 45 guanines from the total, which leaves us with 10 base pairs for adenine-thymine pairing.<\/p>\n\n\n\n<p>Because the number of adenines is equal to the number of thymines, there must be 5 adenines and 5 thymines in the molecule.<\/p>\n\n\n\n<p>Thus, there are <strong>5 adenines<\/strong> in this DNA sequence.<\/p>\n\n\n\n<p>Explanation:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Total base pairs = 100<\/li>\n\n\n\n<li>Cytosine = 45<\/li>\n\n\n\n<li>Guanine = 45<\/li>\n\n\n\n<li>Adenine + Thymine = 100 &#8211; (45 + 45) = 10<\/li>\n\n\n\n<li>Adenine = Thymine = 10 \/ 2 = 5<\/li>\n<\/ul>\n\n\n\n<p>This explanation follows from the structure of DNA and the way bases pair in complementary strands, ensuring the molecule is stable and functions properly in processes like replication and transcription.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Assume that a 100-base pair DNA double helix contains 45 cytosines. How many adenines are there? The correct answer and explanation is: In a DNA double helix, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). According to Chargaff&#8217;s rules, the amount of adenine equals the amount of thymine, and the [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-264771","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/264771","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=264771"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/264771\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=264771"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=264771"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=264771"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}