Mitochondrial electron transport chain: schematic representation of the mitochondrial electron transport chain involved in oxidative phosphorylation. CI and II (Complexes I and II) transport electrons (e-s) generated by the conversion of NADH to NAD+ (CI) or FADH2 to FAD (CII) through Q (ubiquinone), CIII, Cyt c (cytochrome c) and finally CIV, which uses an e- to convert O2 to H2O. During electron transfer, CI, II, and IV pump protons (H+s) from the mitochondrial matrix into the intermembrane space generating a H+ concentration gradient that drives the formation of ATP from ADP by ATP-synthase (Complex V).
