The number of peptide linkages in a tripeptide containing three amino acids is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 2
A peptide linkage (–CO–NH–) is an amide bond formed when the –COOH group of one amino acid reacts with the –\( \ce{NH2} \) group of the next, with loss of a water molecule. Each new linkage joins one more amino acid to the chain, so a chain of n amino acids has n − 1 peptide linkages.
For example, glycine, alanine and glycine give the tripeptide Gly-Ala-Gly:
\( \displaystyle \ce{H2N-CH2-CO-NH-CH(CH3)-CO-NH-CH2-COOH} \)
There are two –CO–NH– groups. So a tripeptide of three amino acids has 3 − 1 = 2 peptide linkages.
NCERT (2026-27 edition):
Structure of Proteins – …
