{"id":2266,"date":"2016-05-20T20:57:31","date_gmt":"2016-05-20T20:57:31","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/biologyxwaymakerxmaster\/?post_type=chapter&#038;p=2266"},"modified":"2024-04-26T22:24:37","modified_gmt":"2024-04-26T22:24:37","slug":"reading-metabolism-without-oxygen-2","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-biology1\/chapter\/reading-metabolism-without-oxygen-2\/","title":{"raw":"Metabolism without Oxygen","rendered":"Metabolism without Oxygen"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Describe fermentation as anaerobic energy production<\/li>\r\n<\/ul>\r\n<\/div>\r\n\r\n[caption id=\"attachment_1758\" align=\"alignright\" width=\"300\"]<img class=\"size-medium wp-image-1758\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/110\/2016\/05\/03200853\/Figure_07_05_01-300x233.jpg\" alt=\"This photo shows a bloom of green bacteria in water.\" width=\"300\" height=\"233\" \/> Figure 1. The green color seen in these coastal waters is from an eruption of hydrogen sulfide-producing bacteria. These anaerobic, sulfate-reducing bacteria release hydrogen sulfide gas as they decompose algae in the water. (credit: modification of work by NASA\/Jeff Schmaltz, MODIS Land Rapid Response Team at NASA GSFC, Visible Earth Catalog of NASA images)[\/caption]\r\n\r\nIn aerobic respiration, the final electron acceptor is an oxygen molecule, O<sub>2<\/sub>. If aerobic respiration occurs, then ATP will be produced using the energy of high-energy electrons carried by NADH or FADH<sub>2<\/sub> to the electron transport chain. If aerobic respiration does not occur, NADH must be reoxidized to NAD<sup>+<\/sup> for reuse as an electron carrier for the glycolytic pathway to continue. How is this done? Some living systems use an organic molecule as the final electron acceptor. Processes that use an organic molecule to regenerate NAD<sup>+<\/sup> from NADH are collectively referred to as\u00a0<strong>fermentation<\/strong>. In contrast, some living systems use an inorganic molecule as a final electron acceptor. Both methods are called <strong>anaerobic cellular respiration<\/strong> in which organisms convert energy for their use in the absence of oxygen.\r\n<h2>Anaerobic Cellular Respiration<\/h2>\r\nCertain prokaryotes, including some species of bacteria and Archaea, use anaerobic respiration. For example, the group of Archaea called methanogens reduces carbon dioxide to methane to oxidize NADH. These microorganisms are found in soil and in the digestive tracts of ruminants, such as cows and sheep. Similarly, sulfate-reducing bacteria and Archaea, most of which are anaerobic (Figure 1), reduce sulfate to hydrogen sulfide to regenerate NAD<sup>+<\/sup> from NADH.\r\n<div class=\"textbox shaded\"><a href=\"https:\/\/courses.cit.cornell.edu\/biomi290\/z.OldWebSite\/MOVIES\/GLYCOLYSIS.HTML\" target=\"_blank\" rel=\"noopener\">Visit this\u00a0site to see anaerobic cellular respiration in action.<\/a><\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Describe fermentation as anaerobic energy production<\/li>\n<\/ul>\n<\/div>\n<div id=\"attachment_1758\" style=\"width: 310px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1758\" class=\"size-medium wp-image-1758\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/110\/2016\/05\/03200853\/Figure_07_05_01-300x233.jpg\" alt=\"This photo shows a bloom of green bacteria in water.\" width=\"300\" height=\"233\" \/><\/p>\n<p id=\"caption-attachment-1758\" class=\"wp-caption-text\">Figure 1. The green color seen in these coastal waters is from an eruption of hydrogen sulfide-producing bacteria. These anaerobic, sulfate-reducing bacteria release hydrogen sulfide gas as they decompose algae in the water. (credit: modification of work by NASA\/Jeff Schmaltz, MODIS Land Rapid Response Team at NASA GSFC, Visible Earth Catalog of NASA images)<\/p>\n<\/div>\n<p>In aerobic respiration, the final electron acceptor is an oxygen molecule, O<sub>2<\/sub>. If aerobic respiration occurs, then ATP will be produced using the energy of high-energy electrons carried by NADH or FADH<sub>2<\/sub> to the electron transport chain. If aerobic respiration does not occur, NADH must be reoxidized to NAD<sup>+<\/sup> for reuse as an electron carrier for the glycolytic pathway to continue. How is this done? Some living systems use an organic molecule as the final electron acceptor. Processes that use an organic molecule to regenerate NAD<sup>+<\/sup> from NADH are collectively referred to as\u00a0<strong>fermentation<\/strong>. In contrast, some living systems use an inorganic molecule as a final electron acceptor. Both methods are called <strong>anaerobic cellular respiration<\/strong> in which organisms convert energy for their use in the absence of oxygen.<\/p>\n<h2>Anaerobic Cellular Respiration<\/h2>\n<p>Certain prokaryotes, including some species of bacteria and Archaea, use anaerobic respiration. For example, the group of Archaea called methanogens reduces carbon dioxide to methane to oxidize NADH. These microorganisms are found in soil and in the digestive tracts of ruminants, such as cows and sheep. Similarly, sulfate-reducing bacteria and Archaea, most of which are anaerobic (Figure 1), reduce sulfate to hydrogen sulfide to regenerate NAD<sup>+<\/sup> from NADH.<\/p>\n<div class=\"textbox shaded\"><a href=\"https:\/\/courses.cit.cornell.edu\/biomi290\/z.OldWebSite\/MOVIES\/GLYCOLYSIS.HTML\" target=\"_blank\" rel=\"noopener\">Visit this\u00a0site to see anaerobic cellular respiration in action.<\/a><\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-2266\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Biology 2e. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\">http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Access for free at https:\/\/openstax.org\/books\/biology-2e\/pages\/1-introduction<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":17,"menu_order":18,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Biology 2e\",\"author\":\"\",\"organization\":\"OpenStax\",\"url\":\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Access for free at https:\/\/openstax.org\/books\/biology-2e\/pages\/1-introduction\"}]","CANDELA_OUTCOMES_GUID":"b79c1ab3-db46-4b97-b3af-8b8b666ee7d8, 63e78bfb-3e20-48b8-a4a9-d5ac050636dc","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-2266","chapter","type-chapter","status-publish","hentry"],"part":168,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters\/2266","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":10,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters\/2266\/revisions"}],"predecessor-version":[{"id":5919,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters\/2266\/revisions\/5919"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/parts\/168"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters\/2266\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/media?parent=2266"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapter-type?post=2266"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/contributor?post=2266"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/license?post=2266"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}