NADH and FADH2 act as reducing equivalent that means these two compounds donate electron to other molecule such as oxygen to reduce later into water by oxidizing themselves.
Explanation:
NADH and FADH2 are the reduced form of NAD+ and FAD which are used as co enzymes.
NADH and FADH2 are formed during glycolysis and TCA cycle.These 2 reducing equivalent enters Electron transport Chain and donate electrons, these donated electrons are then transported through various electron carriers to final electron acceptor oxygen thus reducing oxygen to water and also regenerate their original form respectively called NAD+ and FAD.
