Question

Electron Transport System (ETS) is located in mitochondrial
(А) Outer membrane
(B) Inter membrane space
(C) Inner membrane
(D) Matrix

Answer 1

Hint: Cytochromes are the main electron carriers present in the Electron transport chain. Minerals associated with cytochrome are Fe (iron) and Cu(copper). Cytochromes are Iron-containing molecules that are involved in electron transferring. Cytochromes were discovered by McCann and the term cytochrome was given by K.P. Kailin.

Complete answer:
The electron transport system usually takes place in the mitochondria. It occurs as the last step of aerobic respiration. The electron transport system contains a series of properly arranged 9 electron carriers that are commonly called Coenzymes, in the inner membrane of the mitochondria, including the cristae of mitochondria. Mitochondria are surrounded by two membranes outer and inner. Inner membrane forms a number of infoldings called cristae. The coenzymes are only found in the inner membrane.

Diagram showing structure of mitochondria

Now let us match this position with the given options: -
A) Outer membrane: This membrane is generally made up of 40% lipid and 60% proteins. So, electron transport chains do not occur. Thus, they do not have cytochromes. Thus, this option is not correct.
B) Inter membrane space: The space between two of the membranes of the mitochondria is termed as the Inter membrane space. It does not contain cytochrome so electron transport chains don’t occur here.
C) Inner membrane: Mitochondria are surrounded by two membranes outer and inner. Inner membrane forms a number of infoldings called cristae. This crista contains coenzymes for electron transport chains so cytochrome occurs here. Thus, this option is correct.
D) Matrix: Matrix lies inside the inner membrane of mitochondria but in matrix electron transport chains do not occur. Thus, they do not have cytochromes. Thus, this option is not correct.

Thus the correct answer is option (C).

Note: Cytochromes are mostly heme containing compounds that are proteinaceous in nature. They occur in bacteria and in eukaryotes in organelle known as mitochondria. Mitochondria are the main site of aerobic respiration. They are miniature biochemical factories where food stuff are oxidised to carbon dioxide and water