Oxidative phosphorylation

Oxidative phosphorylation (or OXPHOS in short) is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy which is used to produce adenosine triphosphate (ATP). This process takes place in the mitochondria in eukaryotic cells.

Overview

In eukaryotes, oxidative phosphorylation occurs in the mitochondrion. It is the final metabolic pathway of cellular respiration, after glycolysis and the citric acid cycle (or Krebs cycle), and is the primary method of producing ATP in most aerobic organisms.

Process

Oxidative phosphorylation involves the reduction of oxygen to water, using reducing equivalents produced in the citric acid cycle, and the generation of ATP. The process consists of an electron transport chain and the process of chemiosmosis.

Electron Transport Chain

The electron transport chain is a series of protein complexes and small organic molecules embedded in the inner mitochondrial membrane. They accept and donate electrons easily, passing them along the chain from one complex to another.

Chemiosmosis

Chemiosmosis is the movement of ions across a selectively permeable membrane, down their electrochemical gradient. In the case of oxidative phosphorylation, it is the proton gradient that drives ATP synthesis.

Role in Disease

Defects in oxidative phosphorylation system are associated with a wide variety of clinical disorders. These include Leigh syndrome, neuropathy, ataxia, and retinitis pigmentosa (NARP).

See Also

• Cellular respiration
• Mitochondrion
• Electron transport chain
• Chemiosmosis

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