Read the Proton Gradient That Powers ATP
Oxidative phosphorylation couples electron transport to ATP synthesis through a proton gradient across the inner mitochondrial membrane.
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Build and spend the gradient
Electron transport pumps protons to the intermembrane space. Their return through ATP synthase drives phosphorylation of ADP. The proton gradient, rather than a high-energy protein bond or ADP export, is the immediate energy source.
Separate phosphorylation mechanisms
Photophosphorylation and oxidative phosphorylation use ATP synthase. Substrate-level phosphorylation transfers a phosphate directly from a metabolic intermediate to ADP/GDP.
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- ✓Gradient across the inner mitochondrial membrane.
- ✓Proton return through ATP synthase powers ATP formation.
- ✓Substrate-level phosphorylation does not require ATP synthase.
Chemiosmosis explains ATP synthesis; it is not itself a carbon-oxidation stage.
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