One turn of Krebs' cycle for the oxidation of 1 mol of sucrose produce how many ATP molecules ?

Options

A. 12
B. 24
C. 22
D. 11

Explanation

To determine how many ATP molecules are produced from one turn of the Krebs cycle for the oxidation of 1 mole of sucrose, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Krebs Cycle**: The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions used by all aerobic organisms to generate energy. It occurs in the mitochondria and is a crucial part of cellular respiration.

2. **Oxidation of Sucrose**: Sucrose (C12H22O11) is a disaccharide composed of glucose and fructose. When sucrose is metabolized, it is first hydrolyzed into glucose and fructose, which can then enter the Krebs cycle.

3. **Glucose and the Krebs Cycle**: One molecule of glucose (C6H12O6) produces two molecules of pyruvate during glycolysis. Each pyruvate then enters the Krebs cycle, resulting in two turns of the cycle for one molecule of glucose.

4. **Production of NADH and FADH2**: In one turn of the Krebs cycle, the following energy carriers are produced:
- 3 NADH
- 1 FADH2
- 1 ATP (or GTP)

5. **ATP Yield from NADH and FADH2**:
- Each NADH can generate approximately 2.5 to 3 ATP through oxidative phosphorylation in the electron transport chain.
- Each FADH2 can generate approximately 1.5 to 2 ATP.

6. **Calculating ATP from One Turn of the Krebs Cycle**:
- From 3 NADH: 3 NADH × 2.5 ATP = 7.5 ATP (or 3 × 3 = 9 ATP)
- From 1 FADH2: 1 FADH2 × 1.5 ATP = 1.5 ATP (or 1 × 2 = 2 ATP)
- From 1 ATP produced directly in the cycle.

7. **Total ATP Calculation**:
- Total ATP from one turn of the Krebs cycle = ATP from NADH + ATP from FADH2 + ATP produced directly
- Using the lower estimates: 7.5 ATP (from NADH) + 1.5 ATP (from FADH2) + 1 ATP = 10 ATP.
- Using the higher estimates: 9 ATP (from NADH) + 2 ATP (from FADH2) + 1 ATP = 12 ATP.

8. **Considering Sucrose**: Since one mole of sucrose leads to two turns of the Krebs cycle (due to the breakdown into glucose and fructose), we need to multiply the ATP yield from one turn by 2.

9. **Final Calculation**:
- For 12 ATP from one turn, for sucrose it would be 12 ATP × 2 = 24 ATP.
- For 10 ATP from one turn, for sucrose it would be 10 ATP × 2 = 20 ATP.

### Conclusion:
The oxidation of 1 mole of sucrose through the Krebs cycle can yield approximately 24 ATP molecules when considering the higher estimates.