Krebs cycle is involved during the oxidation of

Options

A. Proteins and fats only
B. Carbohydrates and fats only
C. Carbohydrates only
D. Carbohydrates, fats and proteins

Answer

**Step-by-Step Solution:**

1. **Understanding the Krebs Cycle**: The Krebs cycle, also known as the citric acid cycle or TCA cycle, is a series of chemical reactions that play a crucial role in cellular respiration. It is responsible for the oxidative metabolism of various macromolecules.

2. **Substrates for the Krebs Cycle**: The cycle primarily oxidizes acetyl-CoA, which can be derived from three main types of macromolecules: carbohydrates, fats, and proteins.

3. **Carbohydrates**: When carbohydrates are metabolized, they are broken down into glucose, which is then converted into pyruvate through glycolysis. Pyruvate is subsequently converted into acetyl-CoA, which enters the Krebs cycle.

4. **Fats**: Fats are broken down through a process called beta-oxidation, which converts fatty acids into acetyl-CoA. This acetyl-CoA then enters the Krebs cycle.

5. **Proteins**: Proteins are broken down into amino acids, which can be deaminated (removal of the amino group) and converted into various intermediates that can also form acetyl-CoA. These intermediates can then enter the Krebs cycle.

6. **Conclusion**: Since the Krebs cycle can utilize acetyl-CoA derived from carbohydrates, fats, and proteins, it is involved in the oxidation of all three macromolecules.

7. **Final Answer**: Therefore, the correct option is that the Krebs cycle is involved during the oxidation of carbohydrates, fats, and proteins.

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