Solution

Cytochromes are haemoproteins containing haeme groups and are primarily responsible for the generation of ATP via electron transport.
They are found either as monomeric proteins (e.g., cytochrome c) or as subunits of bigger enzymatic complexes that catalyze redox reactions. Cytochromes were initially described in 1884 by MacMunn as respiratory pigments. They are found in the cristae of mitochondria.