Question

Which of these statements is incorrect ?

• A. Enzymes of TCA cycle are present in mitochondrial matrix.
• B. Glycolysis operates as long as it is supplied with NAD that can pick up hydrogen atoms.
• C. Glycolysis occurs in cytosol.
• D. Oxidative phosphorylation takes place in outer mitochondrial membrane.

Answer 1

The Correct Option is D

To determine which statement is incorrect, we need to evaluate each given option about cellular respiration, focusing primarily on the location of different processes within the cell.

1. Enzymes of TCA cycle are present in mitochondrial matrix.
   This statement is correct. The tricarboxylic acid (TCA) cycle, also known as the Krebs cycle, occurs within the mitochondrial matrix. Enzymes involved in the TCA cycle are indeed located in this area of the mitochondria. \[\text{Mitochondrial matrix} \] is the innermost compartment of the mitochondrion, where this cycle takes place.
2. Glycolysis operates as long as it is supplied with NAD that can pick up hydrogen atoms.
   This statement is correct. Glycolysis requires NAD⁺ to accept electrons (in the form of hydrogen atoms) in order to proceed. Without a supply of NAD⁺, glycolysis will halt as the necessary reduction-oxidation reactions can't occur.
3. Glycolysis occurs in cytosol.
   This statement is correct. Glycolysis is the process that breaks down glucose into pyruvate, and it occurs in the cytosol of the cell, outside of the mitochondria.
4. Oxidative phosphorylation takes place in outer mitochondrial membrane.
   This statement is incorrect. Oxidative phosphorylation actually occurs on the \[\text{inner mitochondrial membrane}\], not the outer membrane. The inner membrane contains the electron transport chain and ATP synthase, which are essential for this process.

In conclusion, the incorrect statement is the last one, related to oxidative phosphorylation occurring in the outer mitochondrial membrane.