Question

Which of the following amino acids are both glucogenic and ketogenic?
A. Isoleucine, B. Serine, C. Tryptophan, D. Proline, E. Phenylalanine

• A. A, B and C only
• B. A, C and E only
• C. C and E only
• D. B and D only

Hint:

Memory tool for both: "PITTT" (Phe, Ile, Tyr, Trp, Thr).

Answer 1

The Correct Option is B

Step 1: Concept
Amino acids are classified by their metabolic breakdown products.

Step 2: Meaning
- Glucogenic: Can be converted into glucose (via pyruvate or citric acid cycle intermediates). - Ketogenic: Can be converted into ketone bodies (via acetyl-CoA or acetoacetyl-CoA).

Step 3: Analysis
Some amino acids have carbon skeletons that break down into both types of products. These are: Phenylalanine, Tyrosine, Tryptophan, Isoleucine, and Threonine. From the list: A (Isoleucine), C (Tryptophan), and E (Phenylalanine) fit this description. Serine and Proline are purely glucogenic.

Step 4: Conclusion
The correct set is A, C, and E. Final Answer: (B)