{"id":230800,"date":"2025-06-10T06:19:21","date_gmt":"2025-06-10T06:19:21","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=230800"},"modified":"2025-06-10T06:19:23","modified_gmt":"2025-06-10T06:19:23","slug":"a-small-generic-section-of-the-primary-structure-of-a-helix-is-given-by-amino-acid-amino-acid-amino-acid-amino-acid-amino-acid-amino-acid-amino-acid","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/10\/a-small-generic-section-of-the-primary-structure-of-a-helix-is-given-by-amino-acid-amino-acid-amino-acid-amino-acid-amino-acid-amino-acid-amino-acid\/","title":{"rendered":"A small generic section of the primary structure of a helix is given by amino acid &#8211; amino acid, amino acid, amino acid &#8211; amino acid; amino acid, amino acid"},"content":{"rendered":"\n<p>A small generic section of the primary structure of a helix is given by amino acid &#8211; amino acid, amino acid, amino acid &#8211; amino acid; amino acid, amino acid. Which amino acid residue&#8217;s backbone forms a hydrogen bond with the backbone of the seventh residue?<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-1-color\">The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n<p><strong>Correct Answer:<\/strong> The backbone of the <strong>third<\/strong> amino acid residue forms a hydrogen bond with the backbone of the <strong>seventh<\/strong> residue in an \u03b1-helix.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Explanation<\/h3>\n\n\n\n<p>In an <strong>\u03b1-helix<\/strong>, a common secondary structure in proteins, the <strong>backbone atoms<\/strong> of the polypeptide chain form a regular pattern of <strong>hydrogen bonds<\/strong>. These hydrogen bonds occur between the <strong>carbonyl oxygen (C=O)<\/strong> of one amino acid and the <strong>amide hydrogen (N\u2013H)<\/strong> of another amino acid located <strong>four residues ahead<\/strong> in the sequence.<\/p>\n\n\n\n<p>This pattern can be described as <strong>i \u2192 i+4 hydrogen bonding<\/strong>, where the carbonyl oxygen of residue &#8220;i&#8221; forms a hydrogen bond with the amide hydrogen of residue &#8220;i+4&#8221;. This stabilizes the helical structure by aligning the polypeptide chain into a right-handed coil, with 3.6 amino acids per turn.<\/p>\n\n\n\n<p>In the given sequence format:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">nginxCopyEdit<code>amino acid - amino acid, amino acid, amino acid - amino acid; amino acid, amino acid\n<\/code><\/pre>\n\n\n\n<p>Let&#8217;s identify the positions. Removing the formatting characters and counting the residues, we get a sequence of 7 amino acids:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>amino acid<\/li>\n\n\n\n<li>amino acid<\/li>\n\n\n\n<li>amino acid<\/li>\n\n\n\n<li>amino acid<\/li>\n\n\n\n<li>amino acid<\/li>\n\n\n\n<li>amino acid<\/li>\n\n\n\n<li>amino acid<\/li>\n<\/ol>\n\n\n\n<p>To find which residue forms a hydrogen bond with the <strong>7th residue<\/strong>, we use the i \u2192 i+4 rule in reverse:<br>Let the 7th residue be \u201ci\u201d. Then the residue that formed a hydrogen bond with it is <strong>residue i-4 = residue 3<\/strong>.<\/p>\n\n\n\n<p>Therefore, the <strong>third residue<\/strong>&#8216;s <strong>carbonyl oxygen<\/strong> would have formed a hydrogen bond with the <strong>amide hydrogen<\/strong> of the <strong>seventh residue<\/strong>, helping stabilize the \u03b1-helix.<\/p>\n\n\n\n<p>This hydrogen bonding pattern is crucial for the structural integrity and function of many proteins, contributing to the compact, rod-like shape characteristic of \u03b1-helices. It also allows side chains to extend outward from the helix, facilitating interactions with other molecules.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner4-791.jpeg\" alt=\"\" class=\"wp-image-230801\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>A small generic section of the primary structure of a helix is given by amino acid &#8211; amino acid, amino acid, amino acid &#8211; amino acid; amino acid, amino acid. Which amino acid residue&#8217;s backbone forms a hydrogen bond with the backbone of the seventh residue? The Correct Answer and Explanation is: Correct Answer: 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-230800","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/230800","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=230800"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/230800\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=230800"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=230800"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=230800"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}