The peptidoglycan found in the cell envelope of Gram-negative bacteria is made of: <\/p>\n\n\n\n
a. A polysaccharide comprised of a single carbohydrate and repeating units of diverse peptides <\/p>\n\n\n\n
b. Two N-acetylglucosamine moieties, one of which has a unique substituent and is attached to a peptide <\/p>\n\n\n\n
c. Two N-acetylglucosamine moieties, both of which are attached to a peptide with a 5-glycine extension <\/p>\n\n\n\n
d. Teichoic acids e. None of the above<\/p>\n\n\n\n
The correct answer and explanation is:<\/mark><\/strong><\/p>\n\n\n\n The correct answer is b. Two N-acetylglucosamine moieties, one of which has a unique substituent and is attached to a peptide<\/strong>.<\/p>\n\n\n\n Peptidoglycan, which is a key component of the bacterial cell envelope, plays a vital role in maintaining the cell’s shape and protecting it from osmotic pressure. In Gram-negative bacteria, peptidoglycan is a part of the thin cell wall located between the inner cytoplasmic membrane and the outer membrane.<\/p>\n\n\n\n Peptidoglycan consists of repeating disaccharide units composed of N-acetylglucosamine (GlcNAc)<\/strong> and N-acetylmuramic acid (MurNAc)<\/strong>. These two sugar molecules form a backbone of the structure. The MurNAc unit is linked to a short peptide chain, which typically contains a sequence of amino acids that may vary depending on the bacterial species. In some cases, this peptide is cross-linked to the peptides of adjacent glycan chains, providing structural integrity.<\/p>\n\n\n\n In Gram-negative bacteria, the peptidoglycan layer is relatively thin compared to Gram-positive bacteria. However, it is still crucial for maintaining the cell’s mechanical strength. The structure of the peptidoglycan layer also plays a role in the bacterial resistance to various environmental stresses and antibiotics.<\/p>\n\n\n\n The key point in option b<\/strong> is that one of the N-acetylglucosamine units in the peptidoglycan has a unique substituent that is attached to the peptide chain. This differs from the structure found in Gram-positive bacteria, where the peptidoglycan layer is thicker and often cross-linked with different peptides or glycan chains. Thus, this specific structure in Gram-negative bacteria contributes to their distinct structural and functional characteristics.<\/p>\n\n\n\n Option a<\/strong> is incorrect because it misrepresents the structure by suggesting a polysaccharide made of a single carbohydrate and diverse peptides. Options c<\/strong> and d<\/strong> mention incorrect elements such as glycine extensions and teichoic acids, which are not involved in the peptidoglycan structure in Gram-negative bacteria.<\/p>\n","protected":false},"excerpt":{"rendered":" The peptidoglycan found in the cell envelope of Gram-negative bacteria is made of: a. A polysaccharide comprised of a single carbohydrate and repeating units of diverse peptides b. Two N-acetylglucosamine moieties, one of which has a unique substituent and is attached to a peptide c. Two N-acetylglucosamine moieties, both of which are attached to a […]<\/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-257864","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/257864","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=257864"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/257864\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=257864"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=257864"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=257864"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}