* Electron Carriers and Redox Reactions: Electron carriers are molecules that participate in redox reactions. Redox reactions involve the transfer of electrons.
* Reduction and Energy Storage: When an electron carrier gains an electron (becomes reduced), it gains potential energy. This is because the electron is now in a higher energy state within the molecule.
* Oxidation and Energy Release: When the electron carrier loses an electron (becomes oxidized), it loses potential energy. This energy is released and can be used to drive other reactions.
Examples:
* NADH and FADH2: These are important electron carriers in cellular respiration. They are reduced during glycolysis and the citric acid cycle, storing energy. When they are oxidized in the electron transport chain, this energy is used to produce ATP.
* Cytochromes: These are electron carriers in the electron transport chain. They undergo cyclical oxidation and reduction, transferring electrons and releasing energy.
In summary: The reduced state of an electron carrier represents a storage of energy, while the oxidized state represents a release of energy.
