Glucose Oxidation
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Q: Define glycolysis1.... A: Breakdown of glucose (6C) into 2 molecules of pyruvic acid (3C) in the presence of O2, or 2 molecules of lactic acid (3C) in the absence of O22.
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Q: Where does glycolysis take place?2. A: Cytosol of all cells2.
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Understand:
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Q: What is the net ATP and NADH production in glycolysis?2. A: 2 ATP and 2 NADH2.
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Q: Briefly describe the two phases of glycolysis3. A: Phase 1 (Energy Investment): Glucose is converted into 2 molecules of Glyceraldehyde 3-P, consuming 2 ATPs. Phase 2 (Energy Payoff): Glyceraldehyde 3-P is converted to pyruvate, producing ATP and NADH3....
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Apply:
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Q: How does the availability of oxygen affect the fate of pyruvate?4.... A: In anaerobic conditions, pyruvate is converted to lactic acid. In aerobic conditions, pyruvate enters the mitochondria for oxidative decarboxylation4....
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Q: Explain the energy production in glycolysis under aerobic versus anaerobic conditions7. A: Aerobic: 8 ATP (2 direct, 6 from NADH). Anaerobic: 2 ATP (substrate level phosphorylation)7.
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Analyze:
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Q: How do high levels of ATP and NADH regulate glycolysis?8. A: They downregulate glycolytic enzymes8.
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Q: Why are glucokinase/hexokinase, phosphofructokinase-1, and pyruvate kinase rate-limiting enzymes?9. A: They catalyze irreversible reactions9.
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Evaluate:
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Q: Explain the clinical relevance of inherited pyruvate kinase deficiency9. A: It causes hemolytic anemia because RBCs rely on glycolysis for ATP production9.
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Create:
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Q: Describe how insulin and glucagon affect glycolytic enzymes8.... A: Insulin stimulates, glucagon represses9.
II. Oxidative Decarboxylation of Pyruvic Acid
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Remember:
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Q: Define oxidative decarboxylation of pyruvate and its location6. A: Pyruvate is converted to Acetyl CoA, CO2, and NADH+H in the mitochondria6.
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Q: What enzyme and coenzymes are required for this process?6. A: Pyruvate dehydrogenase complex with NAD, FAD, CoA-SH, TPP, and lipoic acid6.
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Understand:
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Q: What are the products of oxidative decarboxylation of pyruvate?6. A: 1 Acetyl CoA, 1 CO2, and 1 NADH+H6.
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Apply:
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Q: What is the fate of Acetyl CoA and NADH+H produced in this step?6. A: Acetyl CoA enters the Krebs cycle, and NADH+H enters the electron transport chain (ETC)6.
III. Krebs Cycle (TCA Cycle)
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Remember:
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Q: Define Krebs cycle and its location10. A: Complete oxidation of acetyl CoA to 2 CO2, producing ATP, NADH, and FADH2 in the mitochondria10.
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Understand:
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Q: What are the products of one turn of the Krebs cycle from one acetyl CoA?10. A: 2 CO2, 1 ATP, 3 NADH+H, and 1 FADH210.
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Apply:
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Q: Outline the two main phases of the Krebs cycle11. A: Condensation of Acetyl CoA with oxaloacetate to form citrate. Oxidation reactions to regenerate oxaloacetate, releasing 2 CO2, 1 ATP, 3 NADH+H, and 1 FADH211.
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Analyze:
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Q: How is the Krebs cycle regulated?12. A: Allosterically at three irreversible steps: citrate synthase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase12. High ATP or NADH downregulate, while high ADP or NAD upregulate these enzymes12.
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Evaluate:
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Q: Why is the Krebs cycle considered a final common metabolic pathway?11. A: It oxidizes carbohydrates, fats, and proteins11.
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Create:
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Q: Calculate the ATP yield from one molecule of acetyl CoA in the Krebs cycle12. A: 12 ATP (1 ATP from substrate-level phosphorylation, 2 ATP from FADH2, 9 ATP from 3 NADH)12.
IV. Complete Glucose Oxidation
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Remember:
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Q: What are the end products of complete glucose oxidation?13. A: 38 ATP and 6 CO213.
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Understand:
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Q: Summarize the ATP production from glycolysis, oxidative decarboxylation, and the Krebs cycle13. A: Glycolysis: 2 ATP and 6 ATP (from 2 NADH+H). Oxidative Decarboxylation: 6 ATP (from 2 NADH+H). Krebs Cycle: 24 ATP (2 ATP, 2 FADH2, 6 NADH+H)13.
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Analyze:
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Q: How does anaerobic glycolysis compare to aerobic glycolysis in terms of ATP production?13. A: Anaerobic glycolysis produces only 2 ATP, while aerobic glycolysis produces 38 ATP13.