Oxidatie en reductie van organische moleculen

Living organisms break down organic molecules in a series of reactions to generate energy. Many of these reactions are oxidation-reduction reactions or redox reactions.

Oxidation is the removal of electrons from an atom, while reduction is the addition of electrons. Because the number of electrons in a reaction is conserved, oxidation and reduction half-reactions always occur in pairs.

Inside cells, when a molecule gains an electron, it often accepts a proton from its surroundings. This addition of hydrogen is called hydrogenation, and the molecule is reduced. Conversely, when a molecule loses hydrogens, this is a dehydrogenation, and the molecule is oxidized.

Protons and electrons can be transferred to electron-carrying molecules, including coenzymes.

For example, in the dehydrogenation of succinate to fumarate, electrons and protons are transferred to the coenzyme FAD, reducing it to FADH₂. The reduced FADH₂ further transfers the electrons through the electron transport chain and is oxidized back to FAD.