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Pronunciation: si'to-krom

Definition: A class of hemoprotein the principal biologic function of which is electron and/or hydrogen transport by virtue of a reversible valency change of the heme iron. Cytochromes are classified in four groups (a, b, c, and d) according to spectrochemical characteristics; many variants exist, particularly among bacteria and in green plants and algae, one being a variant of the c type cytochrome called cytochrome f. The mitochondrial system of cytochromes provides electron transport through cytochrome c oxidase to molecular oxygen as the terminal electron acceptor (respiration).

[cyto- + G. chroma, color]

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© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.