How many 'H_2 O' molecule are involved in oxidation decarboxylation and Kreb's cycle?

Options

A. 1
B. 4
C. 5
D. 6

Answer

To determine how many water (H₂O) molecules are involved in oxidative decarboxylation and the Krebs cycle, we will analyze each process step by step.

### Step 1: Understand Oxidative Decarboxylation
- **Oxidative Decarboxylation** is the process where pyruvate is converted into acetyl-CoA.
- During this reaction, pyruvate is oxidized, and carbon dioxide (CO₂) is released.
- The enzymes involved include the pyruvate dehydrogenase complex, and coenzymes such as NAD⁺ and CoA are required.
- **Key Point**: No water molecules are involved in this reaction.

### Step 2: Analyze the Krebs Cycle
- The **Krebs Cycle** (also known as the citric acid cycle or TCA cycle) begins with the combination of acetyl-CoA and oxaloacetate to form citrate.
- The cycle involves several steps, including the conversion of citrate to isocitrate, then to alpha-ketoglutarate, and so on, eventually regenerating oxaloacetate.
- Throughout the cycle, several products are generated, including NADH, FADH₂, ATP (or GTP), and CO₂.

### Step 3: Identify Water Involvement in the Krebs Cycle
- In the Krebs cycle, water is specifically involved in the conversion of fumarate to malate.
- During this step, one water molecule is added to fumarate to form malate.
- **Key Point**: Only one water molecule is involved in the entire Krebs cycle.

### Conclusion
- In summary, during oxidative decarboxylation, no water molecules are involved.
- In the Krebs cycle, only one water molecule is involved in the conversion of fumarate to malate.
- Therefore, the total number of water molecules involved in both processes is **1**.

### Final Answer
**1 H₂O molecule is involved in oxidation decarboxylation and the Krebs cycle.**

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