Mitochondrial Electron Transport Chain
Start with the big picture
The ETC is located in the inner mitochondrial membrane, with electron donors supplied by mitochondrial metabolism. Electrons from NADH enter through Complex I, while FADH₂ electrons enter through Complex II; both routes converge at coenzyme Q and continue through Complex III, cytochrome c, and Complex IV, where oxygen is reduced to water. Proton translocation establishes a gradient that drives ATP synthase, while Complex II itself does not pump protons. The lesson also considers how shuttles affect cytosolic NADH yield, how ADP and oxygen influence respiratory activity, and how inhibitors differ from uncouplers. Additional sections connect reactive oxygen species, mitochondrial genetics, and proton leak with cellular and clinical effects.
What you'll learn
- Trace electron flow from NADH and FADH₂ through the respiratory complexes to oxygen.
- Explain how proton translocation and ATP synthase couple electron transport to phosphorylation.
- Distinguish ETC inhibitors from uncouplers by their effects on the pathway.
- Describe how respiratory control, shuttles, and oxygen availability influence ATP production.
- Recognize selected links between mitochondrial dysfunction, reactive oxygen species, and clinical disease.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
