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Metabolism and Energy Production

Metabolism and Energy Production. Citric Acid Cycle Electron Transport Chain ATP Energy from Glucose Oxidation of Fatty Acids Metabolic Pathways for Amino Acids. Citric Acid Cycle. A reaction series that Operates under aerobic conditions only

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Metabolism and Energy Production

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  1. Metabolism and Energy Production Citric Acid Cycle Electron Transport Chain ATP Energy from Glucose Oxidation of Fatty Acids Metabolic Pathways for Amino Acids

  2. Citric Acid Cycle A reaction series that • Operates under aerobic conditions only • Oxidizes the 2 carbon atoms of acetyl CoA to CO2 • Provides reduced coenzymes O || CH3–C –CoA 2 CO2 , FADH2, 3 NADH, + ATP acetyl CoA

  3. Steps 1-3 in Citric Acid Cycle α-ketoglutarate

  4. Steps 4-5 of citric acid cycle In the next reactions, α-ketoglutarate is oxidized to succinate. α-ketoglutarate succinate

  5. Steps 6-8 of citric acid cycle More oxidations convert succinate to oxaloacetate. The C=C requires FAD.

  6. 1. Acetyl CoA (2C) + oxaloacetate (4C) to citrate (6C) Citrate (6C) to α-ketoglutarate (5C) + CO2 3. α-ketoglutarate (5C) to succinate (4C) + CO2. GDP picks up Pi. Succinate(4C) to fumarate (C=C) to malate Malate to oxaloacetate. Start again. Total: 2CO2 + 3 NADH + 1 FADH2 + GTP Coenzymes 1 NADH 1 NADH 1 GTP 1 FADH2 1 NADH Coenzymes Produced in the Citric Acid Cycle

  7. Learning Check E1 Complete the following statements: • When 1 acetyl CoA enters the citric acid cycle, the C atoms produce ____CO2. • In 1 cycle, a total of ____NADH are produced. • In 1 cycle, a total of ____FADH2 are produced.

  8. Solution E1 Complete the following statements: • When 1 acetyl CoA enters the citric acid cycle, the C atoms produce 2 CO2. • In 1 cycle, a total of 3 NADH are produced. • In 1 cycle, a total of 1 FADH2 are produced.

  9. Regulation of Citric Acid Cycle • Operates when ATP is needed • High levels of ATP and/or NADH inhibit citrate synthetase (first step in cycle) • High levels of ADP and NAD+ activate isocitrate dehydrogenase • Low levels of ATP or high levels of acetyl CoA speed up the cycle to give energy ATP

  10. Electron Transport Chain • A series of electron carriers • Transfers H+ and electrons from coenzymes NADH and FADH2 (citric acid cycle) • Energy released along chain to make ATP NADH + 3 ADP NAD+ + 3 ATP FADH2 + 2 ADP FAD + 2 ATP

  11. Electron Carriers • Found in three protein complexes • Attached to inner membrane of mitochondria • H+ move into intermembrane space to create proton gradient • As H+ return to matrix, ATP synthase uses energy to synthesize ATP • Oxidation phosphorylation ADP + Pi + Energy ATP

  12. Enzyme Complexes • NADH dehydrogenase • Cytochrome c reductase 3. Cytochrome c Oxidase Coenzyme A Cytochrome c

  13. Chemiosmotic Model Intermembrane space H+ H+ H+ H+ H+ H+ e- NADH + H+ FADH2 H2O Matrix ADP + P ATP Cytc Q

  14. Learning Check E2 Classify each as (1) a product of the citric acid cycle, (2) a product of the electron transport chain A. CO2 B. FADH2 C. NAD+ D. NADH E. ATP

  15. Solution E2 Classify each as (1) a product of the citric acid cycle, (2) a product of the electron transport chain A. 1 CO2 B. 1 FADH2 C. 2 NAD+ D. 1 NADH E. 2 ATP

  16. ATP Energy from Glycolysis(Aerobic) • In the electron transport system NADH = 3 ATP FADH2 = 2 ATP • Glycolysis Glucose 2 pyruvate + 2 ATP + 2 NADH NADH in cytoplasm FADH2 mitochondria Glucose 2 pyruvate + 6 ATP

  17. ATP Energy from Pyruvate 2 pyruvate 2 acetyl CoA + 2 CO2 + 2 NADH 2 pyruvate 2 acetyl CoA + 2 CO2 + 6 ATP

  18. ATP Energy from Citric Acid Cycle One turn of the citric acid cycle 3 NADH x 3 ATP = 9 ATP 1 FADH2 x 2 ATP = 2 ATP 1 GTP x 1 ATP = 1 ATP Total = 12 ATP Glucose provides two acetyl COA molecules for two turns of citric acid cycle 2 acetyl CoA 24 ATP + 4 CO2

  19. ATP from Glucose For 1 glucose molecule undergoing complete oxidation Glycolysis 6 ATP 2 Pyruvate to 2 Acetyl CoA 6 ATP 2 Acetyl CoA to 4 CO224 ATP Glucose + 6 O2 6 CO2 + 6 H2O + 36 ATP

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