16: The Citric Acid Cycle
- Page ID
- 15024
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The citric acid cycle – also known as the TCA cycle or the Krebs cycle – is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.
- 16.1: Production of Acetyl-CoA (Activated Acetate)
- This page reviews the metabolic processes involved in the oxidative decarboxylation of pyruvate by the pyruvate dehydrogenase complex (PDH). It explains glycolysis, where glucose is converted to pyruvate, and the role of PDH in converting pyruvate to acetyl-CoA, a substrate for the citric acid cycle.
- 16.2: Reactions of the Citric Acid Cycle
- This page provides a comprehensive overview of the citric acid cycle (CAC), also known as the Krebs cycle. It explains the metabolic role of the CAC as a hub that oxidizes acetyl-CoA to CO??? and generates reducing equivalents for ATP production, with emphasis on its integration with carbohydrate, lipid, and protein metabolism. The page discusses enzyme mechanisms and regulation, highlighting the cycle's cyclic structure for sustainable metabolic flux.
- 16.3: Regulation of the Citric Acid Cycle
- The page outlines the regulation of key enzymes in the citric acid cycle and their role in cellular energy metabolism. It covers the regulation of the Pyruvate Dehydrogenase Complex, focusing on its conversion of pyruvate to acetyl-CoA and its regulation through phosphorylation and allosteric effectors. It further discusses the regulation of enzymes like citrate synthase, isocitrate dehydrogenase, and ??-ketoglutarate dehydrogenase, emphasizing feedback inhibition and substrate availability.
- 16.4: Variants of the Citric Acid Cycle
- The page provides a detailed overview of various metabolic shunts and bypass mechanisms related to the citric acid cycle. It covers the glyoxylate shunt, allowing organisms like plants, bacteria, and fungi to use acetate effectively for gluconeogenesis. The GABA shunt integrates nitrogen metabolism with energy production, significant for stress responses and neural function.