Answer: Tryptophan (and tyrosine).
- A Tryptophan (and tyrosine)
- B Glycine, due to its small aliphatic side chain absorbing strongly
- C Alanine, due to its methyl side chain's conjugated system
- D Lysine, due to the aromatic character of its amino side chain
Correct answer: A. Tryptophan (and tyrosine)
Explanation: Aromatic amino acids tryptophan and tyrosine absorb UV light at ~280 nm due to their pi electron systems.
Two amino acids join via a condensation reaction: the carboxyl -OH of one and an amine -H of the other are eliminated as water, leaving a peptide bond (-CO-NH-) linking them into a dipeptide; repeating this builds a full protein chain.
Concept context
The chemistry of life: carbohydrates, proteins, lipids, nucleic acids, enzymes, and vitamins. Understand their structures, classification, and biological functions. Highly relevant for NEET and Class 12 board exams.