cytochrome: Meaning and Definition of

cy•to•chrome

1. any of several carrier molecules in the mitochondria of plant and animal cells, consisting of a protein and an iron-containing porphyrin ring and participating in the stepwise transfer of electrons in oxidation reactions: each cytochrome alternately accepts and releases an electron at a slightly lower energy level in the order designated b, c, c, a, and a. Cf. electron transport.