First oxidative decarboxylation during aerobic respiration occur in

Options

A. cytoplasm
B. mitochondrial inner spac
C. mitochondrial outer space
D. mitochondrial matrix.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks where the first oxidative decarboxylation during aerobic respiration occurs. This process is crucial in the metabolic pathway of cellular respiration.

2. **Defining Oxidative Decarboxylation**: Oxidative decarboxylation is a biochemical process that involves the removal of a carboxyl group from a molecule, resulting in the release of carbon dioxide (CO2) and the oxidation of the remaining molecule.

3. **Identifying the Substrate**: The substrate for oxidative decarboxylation in aerobic respiration is pyruvate, which is produced during glycolysis in the cytoplasm.

4. **Locating the Reaction**: After glycolysis, pyruvate is transported into the mitochondria. The first oxidative decarboxylation of pyruvate occurs when it is converted into acetyl coenzyme A (acetyl-CoA).

5. **Determining the Location**: This conversion of pyruvate to acetyl-CoA occurs in the mitochondrial matrix. The mitochondrial matrix is the innermost compartment of the mitochondria, where several metabolic reactions, including the citric acid cycle, take place.

6. **Conclusion**: Therefore, the first oxidative decarboxylation during aerobic respiration occurs in the mitochondrial matrix.

### Final Answer:
The first oxidative decarboxylation during aerobic respiration occurs in the **mitochondrial matrix**.

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