Question

Enzymes of the electron transport system are present in
(A) Inner mitochondrial membrane
(B) Mitochondrial matrix
(C) Inter-membranous space of the mitochondria
(D) Endoplasmic reticulum

Answer 1

Respiration is an essential activity in every living organism. All living organisms need energy for carrying out daily life activities and they get this energy through respiration. The electron transport system is one of the respiration methods. The ET system is a series of complexes that transfer electrons from an electron donor to electron acceptors via a redox reaction. It resides in mitochondria and provides the site for oxidative phosphorylation.

Complete answer: (A) Inner mitochondrial membrane: The inner mitochondrial membrane is the mitochondrial membrane that separates the mitochondrial matrix from the intermembrane space. It is the site for the electron transport system. It transduces energy through oxidative phosphorylation which involves many enzymes. It produces energy in the form of ATP in eukaryotic cells which is the main process in the ET system.
(B) Mitochondrial matrix: Mitochondrial matrix is the space within the inner membrane. It contains DNA, ribosomes, soluble enzymes, small organic molecules, nucleotide cofactors, and inorganic ions. It is the site of the tricarboxylic acid(TCA). It involves enzymes related to TCA.
(C) Inter-membranous space of the mitochondria: The inner-membrane space is the space occurring between or involving two or more membranes. It helps in coordinating a variety of cellular activities.
(D) Endoplasmic reticulum: It is a cellular organelle that forms a series of flattened sacs within the cytoplasm of eukaryotic cells. It is of two types: smooth endoplasmic reticulum and rough endoplasmic reticulum. Its function is to produce proteins for the rest of the cell.

So, (A) is the correct answer.

Note: In the above, we detailed the electron transfer system. It is an exergonic process accompanied by the release of energy. Here, we get to know about the functions of different parts of mitochondria that are involved in the ET System.