Define the

(i) Peptide linkage is the linkage between the monomeric amino acids in a polypeptide chain. It occurs as an amide formed between carboxyl group (-COOH group) of one amino acid and Amine group (-NH₂) group of another amino acid. Condensation of one water takes place to form peptide linkage, i.e., (-CO-NH-)
(ii) Specific sequence of amino acids in a polypeptide chain is said to be the primary structure of the protein.
(iii) When a protein in its native form, is subjected to change in temperature or change in pH, protein loses its biological activity. This is called denaturation of protein. Denaturation alters the secondary and tertiary structure but primary structure remains the same.

Example- Change of milk into curd