Question

The only 5C intermediate formed during reactions of TCA cycle is ______.

Options

• Oxalosuccinic acid

• α-ketoglutarate

• Succinyl СoA

• Cis - Aconitate

Answer 1

The only 5C intermediate formed during reactions of TCA cycle is α-ketoglutarate.

Explanation:

In the TCA (Krebs) cycle:

• Citrate (6C) → isocitrate (6C)
• Then decarboxylation occurs → forms α-ketoglutarate (5C)
• After that, it becomes succinyl-CoA (4C)

So, α-ketoglutarate is the only 5-carbon intermediate.