How does cellular respiration use oxidation-reduction reactions to release energy?

Cellular respiration utilizes a series of oxidation-reduction (redox) reactions to release energy from food molecules in a controlled manner, preventing the release of a lethal burst of heat that would occur if the process happened all at once.12

The process functions through the following steps:

• Electron Donation: During the breakdown of fuel molecules (such as glucose) in glycolysis and the tricarboxylic acid cycle, high-energy electrons are transferred to coenzymes, primarily NAD+ and FAD, reducing them to NADH and FADH2.31
• The Respiratory Chain: These reduced coenzymes act as electron donors in the electron transport chain, located in the inner mitochondrial membrane. Electrons are passed through a sequence of carriers—including cytochromes—in a series of redox reactions.342
• Energy Conservation: As electrons move from donors to the final acceptor, oxygen, the energy released is used to pump protons across the membrane, creating an electrochemical gradient. This gradient powers ATP synthetase to synthesize ATP, the cell's primary energy currency.542