Uncouplers vs. electron transport chain inhibitors
A drug increases oxygen consumption and heat production in mitochondria while decreasing ATP synthesis. The drug most likely:
Answer A: explanation for every choice
A
Correct. An uncoupler, such as 2,4-dinitrophenol or thermogenin, collapses the proton gradient. The chain speeds up to try to restore it, so O2 use rises and the energy is released as heat.
B
An ATP synthase inhibitor such as oligomycin lets the gradient build up, which backs up the chain and lowers O2 consumption.
C
A complex IV inhibitor such as cyanide stops electron flow, so O2 consumption falls.
D
A complex I inhibitor such as rotenone stops electron flow from NADH, so O2 consumption falls.
TakeawayUncouplers: O2 use up, ATP down, heat up. Chain or ATP synthase inhibitors: O2 use and ATP both down.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb13.