Electron carriers are molecules capable of accepting electrons from one molecule and donating them to another via the process of electron transport.
In cellular respiration, there are two important electron carriers, nicotinamide adenine dinucleotide, in the form of reduced NADH or oxidized NAD+, and flavin adenine dinucleotide, in the form of reduced FADH2 or oxidized FAD. Nicotinamide adenine dinucleotide hydrogen or oxidized Nicotinamide adenine dinucleotide, and flavin adenine dinucleotide, in the form of reduced flavin adenine dinucleotide or oxidized flavin adenine dinucleotide