Respiration & Mitochondrial Inhibitors
Compare oxygen consumption, the proton gradient, and ATP under different disruptions.
What to do when the question looks unfamiliar
- Step 1Ask whether electrons can still reach O₂.
- Step 2Ask whether H⁺ is pumped, trapped, or leaking back.
- Step 3Predict ATP production separately from oxygen consumption.
Track three different readouts
The electron transport chain oxidizes electron carriers, transfers electrons to O₂, and pumps H⁺ from matrix to intermembrane space. H⁺ flows back through ATP synthase, driving ATP production.
Inhibiting oxidative phosphorylation does not automatically stop every source of cellular ATP: substrate-level phosphorylation can still contribute. Pay attention to whether the question measures mitochondrial ATP or total cellular ATP.
Compare a stopped chain, blocked return, and leak
A blocked chain cannot maintain proton pumping or normal O₂ reduction. ATP production by ATP synthase falls as the gradient dissipates.
Blocking ATP synthase reduces ATP and can initially steepen the gradient. With less proton return, the gradient pushes back on pumping and electron transport often slows.
Uncoupling gives H⁺ a route back that bypasses ATP synthase. The gradient drops and ATP production falls even though the chain can still use O₂, often faster when substrate and oxygen are available.