/suy"teuh krohm'/ , n. Biochem.
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 1 , c, a, and a 3 . Cf. electron transport .
[ 1895-1900; CYTO- + -CHROME ]