Which of these statements about TCA cycle is false ?

Options

A. There are three points in the cycle where `NAD^+` is reduced to NADH + H and one point where FAD + is reduced to `FADH_2`
B. During the conversion of succinyl - CoA to succinic acid a molecule of GTP is synthesized.
C. It involves condensation of acetyl group with oxaloacetate acid (OAA) and water to yield citric acid
D. It involves two steps of decarboxylation, one leads to formation of alpha ketoglutaric acid while the other leads to the formation of succinic acid

Answer

To determine which statement about the TCA cycle is false, we will analyze each statement provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding the TCA Cycle**: The TCA cycle, also known as the Krebs cycle or citric acid cycle, is a crucial metabolic pathway that involves the oxidation of acetyl-CoA to produce energy.

2. **Analyzing the Statements**:
- **Statement 1**: "There are three points in the cycle where NAD+ is reduced to NADH and one point where FAD is reduced to FADH2."
- **Analysis**: This statement is true. In the TCA cycle, NAD+ is reduced to NADH at three points (isocitrate to alpha-ketoglutarate, alpha-ketoglutarate to succinyl-CoA, and malate to oxaloacetate). FAD is reduced to FADH2 when succinate is converted to fumarate.

- **Statement 2**: "During the conversion of succinyl-CoA to succinic acid, a molecule of GTP is synthesized."
- **Analysis**: This statement is true. The conversion of succinyl-CoA to succinate involves the synthesis of GTP (or ATP, depending on the organism).

- **Statement 3**: "It involves the condensation of acetyl-CoA with oxaloacetate and water to yield citric acid."
- **Analysis**: This statement is true. The TCA cycle begins with the condensation of acetyl-CoA with oxaloacetate to form citrate (citric acid).

- **Statement 4**: "It involves two steps of decarboxylation, one leads to the formation of alpha-ketoglutaric acid, while the other leads to the formation of succinic acid."
- **Analysis**: This statement is false. The first decarboxylation leads to the formation of alpha-ketoglutarate, but the second decarboxylation leads to the formation of succinyl-CoA, not succinic acid. Succinic acid (succinate) is formed after the conversion of succinyl-CoA.

3. **Conclusion**: The false statement is Statement 4.

### Final Answer:
The false statement about the TCA cycle is Statement 4.

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