# DBT JRF 2020 — Question 18

Exam: DBT JRF 2020 · Section: A · Topic: Biochemistry · Difficulty: Easy

## Question

Which of the following is true for acetyl-CoA?

## Options

- **A.** it is an acetyl group joined with a form of cobalt
- **B.** it is an acetyl group attached to a type of coenzyme
- **C.** it is another name for oxaloacetate
- **D.** it is a protein

## Answer

Option B

## Explanation

Acetyl-CoA (acetyl coenzyme A) is a central metabolic thioester: the acetyl group ( $\text{CH}_3\text{CO}-$ ) is linked via a high-energy thioester bond ( $\Delta G^{\circ\prime} \approx -31.5 \text{ kJ/mol}$ ) to the sulfhydryl group of Coenzyme A (CoA-SH). CoA is a coenzyme derived from pantothenic acid (Vitamin B5), not a protein or cobalt compound. Acetyl-CoA is the entry molecule for the TCA cycle, the precursor for fatty acid and cholesterol synthesis, and is produced by pyruvate decarboxylation, fatty acid β-oxidation, and amino acid catabolism.

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