Figure 2.

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).