Question

Which from following is an essential amino acid?

• A. Tyrosine
• B. Serine
• C. Histidine
• D. Glycine

Hint:

Mnemonic for essential amino acids: PVT TIM HALL (Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Arginine, Leucine, Lysine).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Biologically, amino acids are classified into essential and non-essential amino acids based strictly on whether the human body can synthesize them internally. Essential amino acids cannot be synthesized by the body and must be obtained through the diet.
Step 2: Key Formula or Approach:
Approach: Differentiate between amino acids synthesized by the human metabolic pathways (non-essential) and those that must be obtained from dietary sources (essential) by recalling the standard lists.
Step 3: Detailed Explanation:
Let's review the biochemical classification of the amino acids given in the options: - (A) Tyrosine: This is a non-essential amino acid. The human body can synthesize it internally by hydroxylating another amino acid, phenylalanine. - (B) Serine: This is a non-essential amino acid. It can be readily synthesized in the body from metabolic intermediates like 3-phosphoglycerate. - (C) Histidine: This is classified as an essential amino acid. While adults can synthesize very small amounts, it is not sufficient to meet physiological needs, and it is strictly essential for infants and growing children. - (D) Glycine: This is the simplest amino acid structurally and is non-essential, being readily synthesized in the body from serine.
Step 4: Final Answer:
Histidine is an essential amino acid.