Question

Cytochromes are found in
1. A) lysosomes
2. B) Cristae of mitochondria
3. C) Outer wall of mitochondria
4. D) Matrix of mitochondria

Answer 1

Hint Cytochromes are proteins that have heme as a prosthetic group and whose primary biological activity is electron transport in the cells of mammals, plants, and microbes. The nature of the heme prosthetic groups in different types of cytochromes (a type, b type, and c type) varies.

Complete answer:
The reversible redox transition of the iron in the heme core from ferrous (Fe(II)) to ferric (Fe(III)) oxidation state is linked to cytochrome function. Several more classifications, such as cytochrome and cytochrome P450, can be found in biochemical literature in addition to the IUBMB's four cytochrome classes.
MacMunn first identified cytochromes as respiratory pigments in 1884. Keilin uncovered these respiratory pigments in the 1920s and dubbed them cytochromes, or "cellular pigments." He designated these heme proteins as cytochromes an a (605 nm), b (565 nm), and c (565 nm) based on the position of their lowest energy absorption band in their reduced state (550 nm They are found in mitochondrial cristae.

So, the correct answer is option is B.

Additional information
The heme group is a highly conjugated ring structure that surrounds an iron ion and permits its electrons to be exceptionally mobile. The iron in cytochromes is usually ferrous or ferric with a ferroxo state occurring in catalytic intermediates.
Cytochromes can thus catalyse electron transfer reactions and execute electron transfer reactions by reducing or oxidising their heme iron. The function of cytochromes determines where they are found within the cell. They come in the form of globular and membrane proteins.

Note: The cytochrome P450 family of cytochromes is named after the characteristic Soret peak created by light absorbance at wavelengths near 450 nm when heme iron is reduced (with sodium dithionite) and complexed to carbon monoxide. Steroidogenesis and detoxification are the primary functions of these enzymes.