Question

Determine the correct answer and explain why it is correct. Identify why the other options are not correct.

1. Which one of the following correctly describes how the acetyl-CoA is metabolized in the mitochondria?

1. One molecule of acetyl-CoA produces two molecules of CO₂, three molecules of NADH, one molecule of FAD(2H) and one molecule of ATP.
2. All of the energy for high-energy phosphate bonds is derived from oxidative phosphorylation.
3. NAD⁺ is the only electron acceptor in the cycle.
4. Substrate-level phosphorylation generates one high-energy phosphate bond during the cycle.
5. The TCA cycle requires large amounts of vitamins C and D as coenzymes.

Answer 1

Answer ---- (D) is the correct answer

The questions is related to the tricarboxylic acid cycle which is also called as the citric acid cycle or kreb cycle.

The process of the kreb cycle occurs in the mitochondria and in the mitochondria substrate-level phosphorylation in which energy molecules are produced.

The process of TCA produces the energy from the oxidation of the acetyl coA whice we derived from the food.

The energy is formed in the form of GTP in this process and no in form of ATP where as the process forms the energy from the phosphorylation which is substrate level in the kreb cycle which means that it doesn't need intermediate for the production of GTP molecules , direct it id formed.

So by that option A and B is wrong.

And NAD+ is the main electron acceptor in the cycle but not only because FAD also accepts electron and forms FADH2 as you can see in diagram during the formation of fumerate from succinate so C is also wrong.

And coenzymes are those required for the functioning of the enzymes working in the cycle and dehydrogenase and ketoglutarate is the enzyme which takes place in this cycle and they need VITAMIN B and they do not need vitamin C and D are not required so option D is also wrong.

While as we have seen that the energy molecules are produced with the substrate phosphorylation and forms GTP so the right answer is D.

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