All of these events occur in the conversion of pyruvic acid into Acetyl CoA except -

Options

A. Production of `CO_(2)`
B. Conversion of 3-carbon molecule into a 2C molecule
C. Pyruvate dehydrogenase enzyme complex, several factors like `Mg^(+2),NAD ^(+)` and CoA are needed
D. Site of the reaction is cytosol

Answer

To answer the question about the conversion of pyruvic acid into Acetyl CoA, we need to analyze the events that occur during this process and identify which one does not happen.

### Step-by-Step Solution:

1. **Understanding Pyruvic Acid Conversion**:
- Pyruvic acid, a 3-carbon molecule, is converted into Acetyl CoA, a 2-carbon molecule, during a process known as the link reaction (or pyruvate decarboxylation).

2. **Decarboxylation**:
- During this conversion, one carbon atom is removed from pyruvic acid. This removal occurs through decarboxylation, resulting in the production of carbon dioxide (CO2). Therefore, CO2 is produced in this reaction.

3. **Formation of Acetyl CoA**:
- After the decarboxylation, the remaining 2-carbon molecule (the acetyl group) is then attached to coenzyme A, forming Acetyl CoA. This step is crucial for the continuation of cellular respiration.

4. **Enzymatic Action**:
- The conversion requires the action of the enzyme complex called pyruvate dehydrogenase. This enzyme also requires cofactors such as Mg²⁺ and NAD⁺ for its activity.

5. **Location of the Reaction**:
- The conversion of pyruvic acid to Acetyl CoA occurs in the mitochondrial matrix, not in the cytosol. This is an important distinction because glycolysis occurs in the cytosol, while the link reaction occurs in the mitochondria.

6. **Identifying the Incorrect Event**:
- Given the options, the event that does not occur during the conversion of pyruvic acid to Acetyl CoA is the reaction occurring in the cytosol. This reaction is specifically a mitochondrial process.

### Conclusion:
The event that does not occur in the conversion of pyruvic acid into Acetyl CoA is the reaction taking place in the cytosol.