NADH shuttles and ATP yield
Cytosolic NADH oxidized through the glycerol-3-phosphate shuttle yields less ATP than through the malate–aspartate shuttle. Why?
Answer A: explanation for every choice
A
Correct. Electrons reach ubiquinone through a FAD-linked enzyme, skipping complex I's proton pumping, so the yield is about 1.5 ATP instead of 2.5.
B
The shuttle doesn't consume ATP.
C
NADH cannot cross the inner mitochondrial membrane, which is why shuttles exist.
D
Electrons still pass through complexes III and IV before reaching oxygen.
TakeawayGlycerol-3-phosphate shuttle ≈ 1.5 ATP. Malate–aspartate shuttle ≈ 2.5 ATP.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb121.