Electron Transport and Oxidative Phosphorylation

Electron transport and oxidative phosphorylation re-oxidize nicotinamide adenine dinucleotide (NADH) and FADH₂ and trap the energy released as adenosine triphosphate (ATP). In eukaryotes, electron transport and oxidative phosphorylation occur in the inner membrane of mitochondria whereas in prokaryotes the process occurs in the plasma membrane. The oxidation of a molecule involves the loss of electrons. Oxidative phosphorylation is the name given to the synthesis of ATP that occurs when NADH and FADH₂ are oxidized by electron transport through the respiratory chain. Electron transport is normally tightly coupled to ATP synthesis. Electron transport occurs and pumps out H⁺ ions across the inner mitochondrial membrane but DNP in the same membrane carries the H⁺ ions back into the mitochondrion, preventing formation of a proton gradient. Most of the protein components of the electron transport chain exist as four large protein complexes embedded in the inner mitochondrial membrane called: NADH-Q reductase, Succinate-Q reductase, Q-cytochrome c reductase and Cytochrome c oxidase.