University:
University of Wolverhampton
Course:
4PY019 | Pharmacy
Academic year:

2024
Views:

193

Pages:

8
Author:

Sara

Citric Acid Cycle The citric acid cycle & regulation: Respiration: In aerobic condition, glucose is oxidized to H20 (water) and CO2 (carbon dioxide) —> this aerobic phase of catabolism is called respiration. Cellular Respiration: In biochemical aspect, consuming O2 (oxygen) and producing CO2 is called cellular respiration. Cellular respiration occurs in 3 major stages: 1) Organic fuel molecules (glucose, fatty acids & some amino acids) are oxidized to yield two carbon fragments in the form of the acetyl group —> acetyl-coenzyme A 2) Acetyl groups enter the citric acid cycle, which enzymatically oxidizes them to CO2. The energy released is conserved in the reduced electron carriers —> NADH & FADH2 3) Reduced coenzymes are oxidized, giving up H+ (protons) & electrons. - The electrons are transferred to O2 via a chain of electron-carrying molecules known as —> the respiratory chain - In the course of electron transfer, the large amount of energy is conserved in the form of ATP —> oxidative phosphorylation Production of Acetyl-CoA: Before entering the citric cycle, the carbon skeletons of sugars and fatty acids are degraded to the acetyl group of acetyl-CoA. Many amino acid carbons also enter the cycle this way, —> although several amino acids are degraded to other cycle intermediates. Pyruvate dehydrogenase complex: E1: Pyruvate dehydrogenase E2: Dihydrolipoyl transacetylase E3: Dihydrolipoyl dehydrogenase Reactions of the citric acid cycle: 1) Formation of Citrate: 2) Formation of Isocitrate: 3) Oxidation of Isocitrate to a-Ketoglutarate: 4) Oxidation of a-Ketoglutarate to Succinyl-CoA: 5) Conversion of Succinyl-CoA to Succinate: 6) Oxidation of Succinate to Fumarate: 7) Hydration of Fumarate to Malate: 8) Oxidation of Malate to Oxaloacetate: Overall Diagram of TCA Cycle: The Glyoxylate Cycle: - Plants - Invertebrates - Microorganisms (E.coli & yeast)