ROLE of MITOCHONDRIA in TOXIC OXIDATIVE STRESS

Schematic representation of mitochondrial electron transport chain (ETC) and coupling and uncoupling of oxidative phosphorylation. Reduced substrates NADH and FADH₂ are oxidized, with electrons passing to the enzyme complexes of the ETC and the protons (H⁺) pumped into the intermembrane space of the mitochondrion, forming a large mitochondrial membrane potential known as the proton-motive force. Energy lost by protons re-entering the mitochondrial matrix through ATP synthase (A) is used to power generation of ATP from ADP. Protons may also re-enter the matrix via uncoupling proteins (U), such as UCP2, without production of ATP.