Question -
Answer -
(i) Peptide linkage:
The amide formed between −COOH group of onemolecule of an amino acid and −NH2 group of anothermolecule of the amino acid by the elimination of a water molecule is called apeptide linkage.
(ii) Primary structure:
The primary structure of protein refers to the specificsequence in which various amino acids are present in it, i.e., the sequence oflinkages between amino acids in a polypeptide chain. The sequence in whichamino acids are arranged is different in each protein. A change in the sequencecreates a different protein.
(iii) Denaturation:
In a biological system, a protein is found to have aunique 3-dimensional structure and a unique biological activity. In such asituation, the protein is called native protein. However, when the nativeprotein is subjected to physical changes such as change in temperature orchemical changes such as change in pH, its H-bonds are disturbed. Thisdisturbance unfolds the globules and uncoils the helix. As a result, theprotein loses its biological activity. This loss of biological activity by theprotein is called denaturation. During denaturation, the secondary and thetertiary structures of the protein get destroyed, but the primary structureremains unaltered.
One of the examples of denaturation of proteins is thecoagulation of egg white when an egg is boiled.