Respiratory chain
Respiratory Chain
The Respiratory Chain (pronounced: res-pi-ra-tory chain), also known as the Electron Transport Chain (ETC), is a series of protein complexes and electron carrier molecules within the mitochondrial inner membrane that generate ATP for cellular energy.
Etymology
The term "Respiratory Chain" is derived from the process of cellular respiration, where cells break down molecules to release energy, often in the form of ATP. The "chain" refers to the series of reactions involved in this process.
Function
The primary function of the Respiratory Chain is to convert the energy stored in electrons into ATP. This is achieved through a series of redox reactions that transfer electrons from NADH and FADH2 to oxygen, producing water. The energy released in these reactions is used to pump protons across the mitochondrial inner membrane, creating a proton gradient. This gradient drives the synthesis of ATP via chemiosmosis.
Components
The Respiratory Chain consists of four main protein complexes: Complex I (NADH dehydrogenase), Complex II (Succinate dehydrogenase), Complex III (Cytochrome c reductase), and Complex IV (Cytochrome c oxidase). These complexes are embedded in the inner mitochondrial membrane and work together to transfer electrons and pump protons.
Complex I
Complex I, or NADH dehydrogenase, is the first complex in the Respiratory Chain. It accepts electrons from NADH and transfers them to a lipid-soluble carrier, ubiquinone (Q).
Complex II
Complex II, or Succinate dehydrogenase, is the second complex in the Respiratory Chain. It accepts electrons from FADH2, which are then transferred to ubiquinone (Q).
Complex III
Complex III, or Cytochrome c reductase, is the third complex in the Respiratory Chain. It transfers electrons from ubiquinol (QH2) to a water-soluble electron carrier, cytochrome c.
Complex IV
Complex IV, or Cytochrome c oxidase, is the final complex in the Respiratory Chain. It transfers electrons from cytochrome c to oxygen, the final electron acceptor, producing water.
Related Terms
External links
- Medical encyclopedia article on Respiratory chain
- Wikipedia's article - Respiratory chain
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