Cytochrome

Cytochrome (pronounced: /ˈsaɪtəˌkroʊm/) is a class of proteins that play a crucial role in the electron transport chain of cellular respiration and photosynthesis. The term "cytochrome" is derived from the Greek words "kytos" meaning "cell" and "chroma" meaning "color", referring to the protein's characteristic absorption of light at certain wavelengths.

Etymology

The term "cytochrome" was first used in 1925 by David Keilin to describe the colored compounds he observed in the respiratory chain. The word is derived from the Greek "kytos" meaning "cell" and "chroma" meaning "color". This is due to the characteristic color change observed when these proteins are oxidized or reduced.

Function

Cytochromes function as electron transfer agents in many metabolic pathways, most notably cellular respiration and photosynthesis. They are part of the electron transport chain, where they facilitate the transfer of electrons from one molecule to another, aiding in the production of ATP, the cell's main energy source.

Types of Cytochromes

There are several types of cytochromes, including Cytochrome a, Cytochrome b, and Cytochrome c. Each type has a different role in the electron transport chain and is characterized by a unique heme group.

Cytochrome a

Cytochrome a is found in the mitochondria of eukaryotic cells and is involved in the final step of the electron transport chain, transferring electrons to oxygen to form water.

Cytochrome b

Cytochrome b is also found in the mitochondria and is involved in the first step of the electron transport chain, transferring electrons from NADH or FADH2 to Coenzyme Q.

Cytochrome c

Cytochrome c is a small, soluble protein found in the intermembrane space of mitochondria. It transfers electrons from Cytochrome b-c1 complex to Cytochrome c oxidase.

Related Terms

External links

Medical encyclopedia article on Cytochrome
Wikipedia's article - Cytochrome

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