Conversion of PGA to G - 3 - P in PCR cycle involves

Options

A. Oxidative decarboxylation
B. Decarboxylation and deamination
C. Phoshorylation and reduction
D. Reduction and transamination

Answer

To solve the question regarding the conversion of PGA (3-phosphoglycerate) to G3P (glyceraldehyde-3-phosphate) in the Calvin cycle, we need to understand the biochemical processes involved. Here’s a step-by-step breakdown:

### Step-by-Step Solution:

1. **Identify the Reaction Context**:
- The conversion of PGA to G3P occurs in the Calvin cycle, which is part of photosynthesis in higher plants.

2. **Understand the Components**:
- **PGA (3-phosphoglycerate)**: This is the initial product formed after the fixation of carbon dioxide.
- **G3P (glyceraldehyde-3-phosphate)**: This is the end product that can be used to form glucose and other carbohydrates.

3. **Phosphorylation Process**:
- The first step in the conversion of PGA to G3P involves phosphorylation.
- An ATP molecule donates a phosphate group to PGA, converting it into 1,3-bisphosphoglycerate (1,3-BPG). This reaction is catalyzed by the enzyme phosphoglycerate kinase.

4. **Reduction Process**:
- The next step involves the reduction of 1,3-BPG to G3P.
- This reduction is facilitated by NADPH, which donates electrons (and protons) to 1,3-BPG, converting it into G3P. This step is catalyzed by the enzyme glyceraldehyde-3-phosphate dehydrogenase.

5. **Final Outcome**:
- The overall conversion from PGA to G3P involves two main processes: phosphorylation (adding a phosphate group) and reduction (gaining electrons).
- Therefore, the correct answer to the question is that the conversion of PGA to G3P involves **phosphorylation and reduction**.

### Final Answer:
The conversion of PGA to G3P in the Calvin cycle involves **phosphorylation and reduction**.

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