The electron transport system (ETS) in the inner mitochondrial membrane.

(A) Electron micrograph of a human cell section showing three mitochondria. (B) Scheme of the protein complexes that form the ETS, showing the mitochondrial membranes in blue and red; NADH dehydrogenase in light green; succinate dehydrogenase in dark green; the complex formed by acyl-CoA dehydrogenase, electron transfer flavoprotein (ETFP), and ETFP-ubiquinone oxidoreductase in yellow and orange; ubiquinone in green labeled with a Q; cytochrome c reductase in light blue; cytochrome c in dark blue labeled with cytC; cytochrome c oxidase in pink; and the ATP synthase complex in lilac. The flux of electrons is represented by red arrows and e^-, and the flux of protons is represented by red arrows and H⁺.