ATP as well as NADPH ` + H^(+)` both are required during the conversion of _______ in `C_(3) ` cycle

Options

A. RuBP + ` CO_(2) to 2 xx ` PGA
B. `PGA to PGAL`
C. `PGAL to DHAP`
D. Fructose 1, 6 biphosphate ` to `Glucose

Answer

To answer the question regarding the conversion that requires ATP and NADPH + H⁺ in the C3 cycle, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding the C3 Cycle**: The C3 cycle, also known as the Calvin cycle, is a crucial part of photosynthesis that occurs in higher plants. It primarily involves the fixation of carbon dioxide (CO₂) and the conversion of this CO₂ into glucose.

2. **Initial Reaction**: The cycle begins with the reaction of ribulose bisphosphate (RuBP) with CO₂, which is catalyzed by the enzyme ribulose bisphosphate carboxylase/oxygenase (RuBisCO). This reaction produces 3-phosphoglycerate (3-PGA), which is a 3-carbon compound.

3. **Conversion of 3-PGA to 1,3-Bisphosphoglycerate**: The next step involves the conversion of 3-PGA into 1,3-bisphosphoglycerate (1,3-BPG). This reaction requires ATP, which donates a phosphate group to 3-PGA, converting it into 1,3-BPG. During this process, ATP is hydrolyzed to ADP.

4. **Reduction of 1,3-BPG to Glyceraldehyde-3-phosphate (G3P)**: The next step is the reduction of 1,3-BPG to glyceraldehyde-3-phosphate (G3P or PGAL). This reaction requires NADPH + H⁺, which donates electrons to reduce 1,3-BPG into G3P. During this process, NADPH is oxidized to NADP⁺.

5. **Conclusion**: Thus, the conversion that requires both ATP and NADPH + H⁺ in the C3 cycle is the conversion of 3-PGA to G3P (PGAL).

### Final Answer:
ATP as well as NADPH + H⁺ are both required during the conversion of **3-phosphoglycerate (3-PGA)** to **glyceraldehyde-3-phosphate (G3P)** in the C3 cycle.

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