What kind of linkage connects α amino acids in proteins ?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Peptide linkage
Proteins are polymers of α-amino acids joined by the –CO–NH– amide bond, the peptide linkage. A chain of more than ten amino acids is a polypeptide, and a polypeptide with more than about a hundred amino acids is a protein.
Why the other options are incorrect
Option (1) Glycosidic linkage — Incorrect. A glycosidic linkage (an oxygen bridge) joins monosaccharide units in carbohydrates such as sucrose, starch and cellulose. It is not found between amino acids.
Option (3) Nucleoside linkage — Incorrect. A nucleoside is a nitrogenous base joined to a pentose sugar; this is not a bond between amino acids.
Option (4) Nucleotide linkage — Incorrect. In nucleic acids, nucleotides are joined by phosphodiester linkages; this is not a bond between amino acids.
NCERT (2026-27 edition):
Structure of Proteins
