The first pentose sugar formed in PPP of respiration in

Options

A. Ribulose 5-phosphate
B. Ribose 5-phosphate
C. Xylulose 5-phosphate
D. Deoxyribose 5-phosphate

Answer

### Step-by-Step Solution:

1. **Understanding the Pentose Phosphate Pathway (PPP)**:
- The Pentose Phosphate Pathway is a metabolic pathway that generates NADPH and pentoses (5-carbon sugars), which are essential for various biosynthetic processes.

2. **Starting Material**:
- The pathway begins with glucose 6-phosphate, which is derived from glucose.

3. **First Reaction**:
- The first step involves the oxidation of glucose 6-phosphate. This reaction is catalyzed by the enzyme glucose 6-phosphate dehydrogenase and requires NADP+ as a coenzyme.
- The product of this reaction is 6-phosphoglucono-δ-lactone.

4. **Second Reaction**:
- The 6-phosphoglucono-δ-lactone is then hydrolyzed to form 6-phosphogluconic acid. This reaction does not involve any specific enzyme and is a simple hydrolysis.

5. **Third Reaction**:
- The 6-phosphogluconic acid undergoes oxidative decarboxylation, catalyzed by the enzyme 6-phosphogluconate dehydrogenase.
- This reaction produces ribulose 5-phosphate, along with NADPH and carbon dioxide.

6. **Conclusion**:
- The first pentose sugar formed in the Pentose Phosphate Pathway is ribulose 5-phosphate.

### Final Answer:
The first pentose sugar formed in the PPP of respiration is **ribulose 5-phosphate**.

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