Question

Enzymes of citric acid cycle or Kreb's cycle occur in

• A. Outer mitochondrial membrane
• B. Inner mitochondrial membrane
• C. Inter membrane space
• D. Mitochondrial matrix

Answer 1

The correct option is D Mitochondrial matrix

The citric acid cycle is also known as Kreb's cycle or tricarboxylic acid cycle is a series of enzyme-catalyzed reactions that occur in the mitochondrial matrix. It consists of 8 cyclic steps each of which is catalyzed by the specific enzyme. In Krebs cycle, the entrant molecule is 2-carbon acetyl coenzyme A and receptor molecule is 4-carbon oxaloacetic acid. All the enzymes of Krebs cycle are soluble proteins which are located in the mitochondrial matrix space except succinate dehydrogenase which is an integral membrane protein that is firmly attached to the inner surface of the inner mitochondrial membrane where it communicates directly with components in the respiratory chain.

Thus, the correct answer is option D.