Question

Which of the following reaction occurs during conversion of $\alpha$-ketoglutarate $\rightarrow$ Succinyl Co-A?

• A. Decarboxylation
• B. Oxidative decarboxylation
• C. Phosphorylation
• D. Oxidative phosphorylation

Hint:

Krebs cycle key step: $\alpha$-ketoglutarate $\rightarrow$ Succinyl Co-A always involves CO$_2$ release + NADH formation.

Answer 1

The Correct Option is B

Concept:
The Krebs cycle involves several steps where carbon dioxide is released and oxidation occurs.

Step 1: Understand the reaction. Conversion of $\alpha$-ketoglutarate to succinyl Co-A involves:
• Removal of $CO_2$ (decarboxylation)
• Oxidation (NAD$^+$ reduced to NADH)

Step 2: Identify reaction type. Since both oxidation and decarboxylation occur simultaneously, it is called: \[ \text{Oxidative decarboxylation} \]

Step 3: Analyze options.
• (A) Decarboxylation → Incomplete description $\times$
• (B) Oxidative decarboxylation → Correct \checkmark
• (C) Phosphorylation → Not involved $\times$
• (D) Oxidative phosphorylation → Occurs in ETS $\times$

Step 4: Conclusion. \[ \text{Reaction type = Oxidative decarboxylation} \]