Turns of Krebs cycle required for complete oxidation of one molecule of glucose are

Options

A. 2
B. 3
C. 4
D. 6

Answer

To determine the number of turns of the Krebs cycle required for the complete oxidation of one molecule of glucose, we can break down the process step-by-step:

### Step-by-Step Solution:

1. **Understanding Glycolysis**:
- The first step in the oxidation of glucose is glycolysis, where one molecule of glucose (C6H12O6) is converted into two molecules of pyruvic acid (C3H4O3).
- **Hint**: Remember that glycolysis occurs in the cytoplasm and produces pyruvate.

2. **Formation of Acetyl CoA**:
- Each pyruvic acid molecule is then converted into acetyl CoA (C2H3O-CoA) before entering the Krebs cycle. This conversion also releases carbon dioxide (CO2).
- Since one glucose molecule produces two pyruvic acids, it will yield two molecules of acetyl CoA.
- **Hint**: Acetyl CoA is the entry molecule for the Krebs cycle.

3. **Krebs Cycle Turns**:
- Each molecule of acetyl CoA that enters the Krebs cycle results in one complete turn of the cycle.
- Therefore, with two molecules of acetyl CoA produced from one molecule of glucose, two turns of the Krebs cycle will occur.
- **Hint**: Each turn of the Krebs cycle processes one acetyl CoA.

4. **Conclusion**:
- Thus, for the complete oxidation of one molecule of glucose, **2 turns of the Krebs cycle** are required.
- **Final Answer**: The correct option is **2**.

### Summary:
- One molecule of glucose → 2 pyruvic acids → 2 acetyl CoA → 2 turns of the Krebs cycle.