{"id":2208,"date":"2018-03-21T20:41:01","date_gmt":"2018-03-21T20:41:01","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-orgbiochemistry\/?post_type=chapter&p=2208"},"modified":"2018-12-10T14:46:15","modified_gmt":"2018-12-10T14:46:15","slug":"20-3-overview-of-stage-ii-of-catabolism","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-monroecc-orgbiochemistry\/chapter\/20-3-overview-of-stage-ii-of-catabolism\/","title":{"raw":"20.3 Overview of Stage II of Catabolism","rendered":"20.3 Overview of Stage II of Catabolism"},"content":{"raw":"
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Learning Objective<\/h3>\r\n
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  1. Describe the role of acetyl-CoA in metabolism.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

    A metabolic pathway<\/span><\/span><\/strong> is a series of biochemical reactions by which an organism converts a given reactant to a specific end product. As you will learn in Section 20.5 \"Stage II of Carbohydrate Catabolism\"<\/a> through Section 20.7 \"Stage II of Protein Catabolism\"<\/a>, there are specific metabolic pathways\u2014which are different for carbohydrates, triglycerides, and proteins\u2014that break down the products of stage I of catabolism (monosaccharides, fatty acids, and amino acids) to produce a common end product, acetyl-coenzyme A (acetyl-CoA) in stage II of catabolism.<\/p>\r\n

    Acetyl-CoA is shown in Figure 20.10 \"The Structure of Acetyl-Coenzyme A (Acetyl-CoA)\"<\/a>. The acetyl unit, derived (as we will see) from the breakdown of carbohydrates, lipids, and proteins, is attached to coenzyme A, making the acetyl unit more reactive. Acetyl-CoA is used in a myriad of biochemical pathways. For example, it may be used as the starting material for the biosynthesis of lipids (such as triglycerides, phospholipids, or cholesterol and other steroids). Most importantly for energy generation, it may enter the citric acid cycle and be oxidized to produce energy, if energy is needed and oxygen is available. The various fates or uses of acetyl-CoA are summarized in Figure 20.11 \"Cell Chemistry\"<\/a>.<\/p>\r\n\r\n

    \r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"1500\"]\"image\" Figure 20.10 The Structure of Acetyl-Coenzyme A (Acetyl-CoA).[\/caption]\r\n\r\n<\/div>\r\n
    \r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"1940\"]\"image\" Figure 20.11 Cell Chemistry.\u00a0Acetyl-CoA plays a variety of roles in cell chemistry.[\/caption]\r\n\r\n<\/div>\r\n
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    Concept Review Exercises<\/h3>\r\n
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      What is a metabolic pathway?<\/p>\r\n\r\n<\/div><\/li>\r\n \t

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      What vitamin is required to make coenzyme A?<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n

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      [reveal-answer q=\"532356\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"532356\"]<\/p>\r\n\r\n

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      1. A metabolic pathway is a series of biochemical reactions by which an organism converts a given reactant to a specific end product.<\/li>\r\n \t
      2. pantothenic acid[\/hidden-answer]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n
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        Key Takeaway<\/h3>\r\n<\/div>\r\n
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