Describe what you understand by primary structure and secondary structure of proteins.

Primary structure of proteins refer to the sequence in which amino acids are joined together by peptide linkage. The sequence of amino acids in primary structure is very specific. Any change in the sequence of amino acids creates a different protein with different biological activity.
Secondary structure of proteins refers to the conformation which arises due to the coiling of polypeptide chain due to intramolecular hydrogen bonding between carbonyl and -NH groups. Depending upon the size of -R group, there are two secondary structures of protein, i.e. α -Helix and β -Pleated sheet like structure