oxidation-reduction reaction - Dictionary of botany

(oxido-reduction, redox reaction) A process in which electrons are transferred from an electron donor or reducing agent to an electron acceptor or oxidizing agent. Oxidation-reduction reactions are major energy supplying reactions in both autotrophic and heterotrophic organisms. In aerobic organisms the final electron acceptor for oxidation-reduction reactions is oxygen. Anaerobic organisms however use an organic compound as a final electron acceptor, e.g. in yeasts acetaldehyde accepts electrons to form ethanol.
In all organisms there are intermediate oxidation-reduction enzymes and coenzymes between the fuel molecules and the final electron acceptor. The most important of these are the pyridine nucleotides (see NAD , NADP ).