Hapetusfosforylaation

Hapetusfosforylaation, also known as oxidative phosphorylation, is a crucial metabolic pathway that generates the majority of adenosine triphosphate (ATP) in aerobic organisms. This process occurs within the mitochondria, specifically across the inner mitochondrial membrane. It involves two main stages: the electron transport chain and chemiosmosis.

In the electron transport chain, high-energy electrons, primarily derived from the oxidation of glucose and fatty acids during cellular respiration, are passed along a series of protein complexes embedded in the inner mitochondrial membrane. As these electrons move from one complex to another, they release energy. This energy is used to pump protons (hydrogen ions) from the mitochondrial matrix into the intermembrane space, creating a proton gradient.

Chemiosmosis is the second stage, where the potential energy stored in the proton gradient is harnessed to synthesize ATP. Protons flow back into the mitochondrial matrix through a specialized enzyme complex called ATP synthase. This flow of protons drives the phosphorylation of adenosine diphosphate (ADP) to ATP, the main energy currency of the cell. Oxygen acts as the final electron acceptor in the electron transport chain, combining with electrons and protons to form water. Without oxygen, this process cannot proceed, leading to a significant reduction in ATP production.