Metabolism & Bioenergetics MCAT Practice Question
A researcher studying cellular respiration observes that a patient's mitochondria have a defect in Complex III of the electron transport chain. This defect prevents proper electron transfer and proton pumping. During aerobic respiration, the patient's cells produce significantly less ATP than normal cells despite adequate glucose availability. Which of the following best explains the reduced ATP yield in this patient's cells?
Answer choices
- AReduced NADH oxidation in the citric acid cycle
- BIncreased lactate production from anaerobic glycolysis
- CInability to synthesize acetyl-CoA from pyruvate
- DDecreased proton gradient across the inner mitochondrial membraneCorrect answer
- EEnhanced glyceraldehyde-3-phosphate dehydrogenase activity
- FImpaired substrate-level phosphorylation in the citric acid cycle
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