Which one of the following amino acids is classified as BOTH glucogenic and ketogenic?

• A Leucine
• B Valine
• C Alanine
• D Isoleucine ✓

Explanation

Isoleucine is degraded to succinyl-CoA (glucogenic) and acetyl-CoA (ketogenic), making it both glucogenic and ketogenic. Leucine is exclusively ketogenic because it yields HMG-CoA and acetyl-CoA with no glucogenic intermediate, which eliminates option A. Valine yields propionyl-CoA and is purely glucogenic, and alanine is the classic purely glucogenic amino acid via pyruvate. Only isoleucine, plus lysine among all twenty, shares the dual pathway with leucine being the trap here.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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