Question

Choose the correct option-

All enzymes of the TCA cycle are located in the mitochondrial matrix except one which is located in the inner mitochondrial membranes in eukaryotes and in the cytosol in prokaryotes. This enzyme is-

• A. malate dehydrogenase
• B. isocitrate dehydrogenase
• C. lactate dehydrogenase
• D. succinate dehydrogenase

Answer 1

The correct option is D

succinate dehydrogenase

The correct option is D.

Explanation of correct option

1. Succinate dehydrogenase helps in the conversion of succinate to fumarate during the Krebs cycle.
2. It simultaneously reduces ubiquinone to ubiquinol.
3. It facilitates energy generation and cellular respiration.
4. Succinate dehydrogenase is located in the inner mitochondrial membrane in eukaryotes and in the cytosol region in prokaryotes.

Explanation of incorrect option

Option A

1. Malate dehydrogenase helps in the conversion of malate to oxaloacetate.
2. It is located in the extra-mitochondrial cytoplasmic region.

Option B

1. Isocitrate dehydrogenase is the tricarboxylic acid enzyme that helps in isocitrate oxidative decarboxylation into carbon dioxide and alpha-ketoglutarate.
2. It is located in the mitochondrial matrix.

Option C

1. Lactate dehydrogenase helps in the oxidation of lactate molecules.
2. It is located in the cytosol and mitochondrial matrix of almost all the body cells.

Final answer: Succinate dehydrogenase is located in the inner mitochondrial membranes in eukaryotes and in the cytosol in prokaryotes.