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Any of a group of cell proteins (hemoproteins) that serve a vital function in the transfer of energy within cells. Hemoproteins are linked to a nonprotein, iron-bearing component (a heme group), which can undergo the reversible oxidation-reduction reactions that yield energy for the cell. Cytochromes are subdivided into three classes depending on what wavelengths of light they absorb. At least 30 different cytochromes have been identified.
This entry comes from Encyclopædia Britannica Concise. For the full entry on cytochrome, visit Britannica.com.