Complete aerobic oxidation of one molecule of glucose yields a net total of either 30 or 32 ATP depending on which factor?
- A Whether the P/O ratio of Complex II is taken as 1.5 or 2.0
- B Whether the hexokinase or glucokinase isoform phosphorylates glucose
- C Whether the tissue uses the malate-aspartate shuttle or the glycerol-3-phosphate shuttle for cytosolic NADH ✓
- D Whether pyruvate enters mitochondria via the MPC or is first transaminated
Correct answer: C. Whether the tissue uses the malate-aspartate shuttle or the glycerol-3-phosphate shuttle for cytosolic NADH
Explanation
Glycolysis produces two cytosolic NADH. Via the malate-aspartate shuttle (liver, heart, kidney) each yields about 2.5 ATP, giving 32 ATP total; via the glycerol-3-phosphate shuttle (muscle, brain) each yields about 1.5 ATP, giving 30 ATP total. Hexokinase versus glucokinase changes Km and regulation but costs the same single ATP, and Complex II FADH2 yield is fixed at roughly 1.5 ATP.
Reference: Lehninger Principles of Biochemistry, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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