Decarboxylation occurs during

Options

A. Glycolysis
B. ETS
C. Krebs cycle
D. All the above

Answer

**Step-by-Step Solution:**

1. **Understanding Decarboxylation**: Decarboxylation is a biochemical reaction that involves the removal of a carboxyl group (-COOH) from a molecule, releasing carbon dioxide (CO2) in the process.

2. **Identifying the Processes**: The question asks during which process decarboxylation occurs. The options provided are glycolysis, ETS (Electron Transport System), Krebs cycle, or all of the above.

3. **Analyzing Glycolysis**: Glycolysis is the metabolic pathway that converts glucose into pyruvate. During glycolysis, there is no decarboxylation; instead, glucose is broken down without the release of CO2.

4. **Analyzing ETS**: The Electron Transport System is primarily involved in the production of ATP through oxidative phosphorylation. It does not involve decarboxylation either.

5. **Analyzing the Krebs Cycle**: The Krebs cycle (also known as the citric acid cycle) involves several steps where decarboxylation occurs. For example, citric acid (a 6-carbon compound) is converted into oxalosuccinic acid (5-carbon), and during this conversion, a molecule of CO2 is released. This process continues as the cycle progresses, with further decarboxylation occurring at various steps.

6. **Conclusion**: Since decarboxylation occurs during the Krebs cycle and not during glycolysis or ETS, the correct answer is the Krebs cycle.

**Final Answer**: C. Krebs Cycle

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