Answer: Lysine.
- A Lysine
- B Glycine
- C Alanine
- D Glutamine
Correct answer: A. Lysine
Explanation: Essential amino acids cannot be synthesised by the human body and must be obtained from diet. Lysine is one of the nine essential amino acids.
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.