Concept:Essential amino acids are those that cannot be synthesized by the human body and must be obtained from diet.
Among the given amino acids, only Threonine is essential, while Serine, Aspartic acid, Glycine, and Alanine are non‑essential.
Explanation:From the pentapeptide structure, the component amino acids are identified as:
Threonine (Thr), Serine (Ser), Aspartic acid (Asp), Glycine (Gly), and Alanine (Ala).
Essential amino acid among these is Threonine. So Y = Threonine.
The sequence is determined by reading the peptide from N‑terminal (left) to C‑terminal (right).
In the given structure, the order is: Thr → Ser → Asp → Gly → Ala.
Thus, the sequence is Thr‑Ser‑Asp‑Gly‑Ala.
Answer:Option D: (Y) = Threonine, Sequence = Thr‑Ser‑Asp‑Gly‑Ala.
