{"id":184766,"date":"2025-01-21T15:20:06","date_gmt":"2025-01-21T15:20:06","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=184766"},"modified":"2025-01-21T15:20:10","modified_gmt":"2025-01-21T15:20:10","slug":"which-statement-best-describes-the-structure-of-a-dna-molecule","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/01\/21\/which-statement-best-describes-the-structure-of-a-dna-molecule\/","title":{"rendered":"Which statement best describes the structure of a DNA molecule"},"content":{"rendered":"\n

Which statement best describes the structure of a DNA molecule <\/p>\n\n\n\n

A. DNA is single-stranded and straight molecule <\/p>\n\n\n\n

B. DNA is a double-stranded molecule that looks like a spiral staircase <\/p>\n\n\n\n

C. DNA is a double stranded molecule that is straight like a ladder <\/p>\n\n\n\n

D. DNA is a single-stranded and curly molecule<\/p>\n\n\n\n

The Correct Answer and Explanation is :<\/strong><\/mark><\/p>\n\n\n\n

The correct answer is:<\/p>\n\n\n\n

B. DNA is a double-stranded molecule that looks like a spiral staircase.<\/strong><\/p>\n\n\n\n

Explanation:<\/h3>\n\n\n\n

DNA, or deoxyribonucleic acid, is the hereditary material in nearly all living organisms. Its structure is famously described as a double helix<\/strong>, which resembles a spiral staircase or twisted ladder.<\/p>\n\n\n\n

    \n
  1. Double-Stranded Molecule<\/strong>: DNA is composed of two long strands of nucleotides that run in opposite directions, making it antiparallel<\/strong>. These strands are held together by hydrogen bonds between complementary nitrogenous bases.<\/li>\n\n\n\n
  2. Nitrogenous Bases<\/strong>: The four bases in DNA are adenine (A)<\/strong>, thymine (T)<\/strong>, cytosine (C)<\/strong>, and guanine (G)<\/strong>. Adenine pairs with thymine (A-T) through two hydrogen bonds, while cytosine pairs with guanine (C-G) through three hydrogen bonds. These base-pairing rules are crucial for DNA replication and maintaining genetic fidelity.<\/li>\n\n\n\n
  3. Helical Shape<\/strong>: The twisted structure results from the specific arrangement of sugar-phosphate backbones and the stacking of nitrogenous bases. The sugar-phosphate backbones form the sides of the “ladder,” while the base pairs form the rungs.<\/li>\n\n\n\n
  4. Importance of the Structure<\/strong>: The double helix structure is not only elegant but also functional. It allows DNA to be compactly stored within the cell nucleus, protects genetic information from damage, and provides a mechanism for accurate replication during cell division.<\/li>\n\n\n\n
  5. Misconceptions About DNA<\/strong>:<\/li>\n<\/ol>\n\n\n\n
      \n
    • It is not single-stranded under normal cellular conditions (option A and D are incorrect).<\/li>\n\n\n\n
    • It is not straight like a ladder; the helical twist is a defining feature (option C is incorrect).<\/li>\n<\/ul>\n\n\n\n

      The discovery of the double-helix structure by James Watson and Francis Crick<\/strong> in 1953, based on Rosalind Franklin’s X-ray diffraction data, was a monumental breakthrough in biology. It revealed how DNA carries genetic information and paved the way for modern molecular biology.<\/p>\n","protected":false},"excerpt":{"rendered":"

      Which statement best describes the structure of a DNA molecule A. DNA is single-stranded and straight molecule B. DNA is a double-stranded molecule that looks like a spiral staircase C. DNA is a double stranded molecule that is straight like a ladder D. DNA is a single-stranded and curly molecule The Correct Answer and Explanation […]<\/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-184766","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/184766","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=184766"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/184766\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=184766"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=184766"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=184766"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}