Chemiosmosis
Electron transport releases energy used to move H⁺ across a membrane. Mitochondria accumulate H⁺ in the intermembrane space; H⁺ flows to the matrix through ATP synthase. Uncouplers dissipate the gradient while electron transport may continue. Blocking ATP synthase initially steepens the gradient, which then slows the chain. Fermentation regenerates NAD⁺ to sustain glycolysis; fermentation itself does not add ATP beyond glycolysis.
MAKE IT CONCRETE
A proton leak reduces ATP yield even if oxygen consumption remains high.
DON’T FALL FOR THIS
Electrons do not flow through ATP synthase. Protons do.