Oxidative Phosphorylation and ATP Synthesis
Start with the big picture
The electron transport chain includes complexes I–IV and the mobile carriers coenzyme Q and cytochrome c; complex V is ATP synthase. Proton pumping at complexes I, III, and IV builds the proton-motive force, which combines membrane potential and a pH gradient. When protons return through ATP synthase, rotation of its membrane component drives conformational changes that support ATP formation. This chemiosmotic coupling does not require a direct chemical intermediate between electron transport and ATP synthesis. ATP output depends in part on the electrons’ entry point and the shuttle used to transfer cytosolic NADH equivalents. ADP availability is a principal regulator. Inhibitors, uncouplers, reactive oxygen species, and mitochondrial DNA mutations are additional topics in the broader lesson.
What you'll learn
- Identify the location and principal components of oxidative phosphorylation.
- Explain how electron flow and proton pumping establish the proton-motive force.
- Describe how ATP synthase uses proton return to support ATP formation.
- Compare the ATP yields associated with NADH and FADH₂ oxidation.
- Recognize how ADP, inhibitors, and uncouplers affect oxidative phosphorylation.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
