How many molecules of ATP will be generated in Krebs cycle ,if a molecule of sucrose is completely oxidised and used as a substrate ?

Options

A. 24
B. 48
C. 2
D. 30

Answer

To determine how many molecules of ATP will be generated in the Krebs cycle when a molecule of sucrose is completely oxidized, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Sucrose Composition**:
- Sucrose is a disaccharide composed of one glucose molecule and one fructose molecule.

2. **Oxidation of Glucose**:
- When glucose is oxidized, it undergoes glycolysis, resulting in the formation of 2 molecules of pyruvate.
- Each pyruvate is then converted to acetyl-CoA, which enters the Krebs cycle.
- From one molecule of glucose, the Krebs cycle generates 24 ATP molecules.

3. **Oxidation of Fructose**:
- Fructose can be converted into fructose-6-phosphate, which also enters glycolysis.
- Similar to glucose, fructose will also yield 2 molecules of pyruvate, which are converted into 2 acetyl-CoA.
- The Krebs cycle will again generate 24 ATP molecules from the oxidation of fructose.

4. **Total ATP from Sucrose**:
- Since both glucose and fructose yield 24 ATP each in the Krebs cycle, the total ATP generated from the complete oxidation of sucrose (glucose + fructose) will be:
\[ 24 \text{ ATP (from glucose)} + 24 \text{ ATP (from fructose)} = 48 \text{ ATP} \]

5. **Conclusion**:
- Therefore, when a molecule of sucrose is completely oxidized, a total of **48 ATP molecules** will be generated in the Krebs cycle.

### Final Answer:
**48 ATP molecules will be generated in the Krebs cycle from the complete oxidation of a molecule of sucrose.**

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