The reaction involved in reduction of `NAD^(+)` is

Options

A. `Glucose rarrGlucose 6-P`
B. Fructose 1,6 diphosphate `---PGAL+DiHAP`
C. `Glucose 6-PrarrFructose 6-P`
D. `PGALrarrPGA.`

Answer

To determine the reaction involved in the reduction of NAD⁺, we need to analyze the provided options based on the glycolysis pathway. Here’s a step-by-step breakdown of the reasoning:

### Step 1: Understand the Role of NAD⁺ in Glycolysis
NAD⁺ (Nicotinamide adenine dinucleotide) acts as an electron carrier in cellular respiration. During glycolysis, it is reduced to NADH when it accepts electrons.

### Step 2: Examine Each Option
1. **Glucose to Glucose 6-Phosphate**:
- This reaction involves the phosphorylation of glucose and uses ATP. NAD⁺ is not involved in this step, so this option is incorrect.

2. **Fructose 1,6-bisphosphate to Glyceraldehyde 3-Phosphate and Dihydroxyacetone Phosphate**:
- This step involves the cleavage of fructose 1,6-bisphosphate into two triose sugars. There is no reduction of NAD⁺ in this reaction, making this option incorrect.

3. **Glucose 6-Phosphate to Fructose 6-Phosphate**:
- This is an isomerization reaction and does not involve the reduction of NAD⁺. Therefore, this option is also incorrect.

4. **Phosphoglyceraldehyde to 1,3-Bisphosphoglyceric Acid**:
- In this reaction, glyceraldehyde 3-phosphate (also known as phosphoglyceraldehyde) is oxidized to 1,3-bisphosphoglyceric acid. During this process, NAD⁺ is reduced to NADH, indicating that this is the correct option.

### Step 3: Conclusion
The correct reaction involved in the reduction of NAD⁺ is:
**Phosphoglyceraldehyde to 1,3-Bisphosphoglyceric Acid** (Option 4).