Proteins are polymers of smaller subunits called amino acids.
The continuous chains of amino acids form peptide chains and then multiple peptide chains club together to form a protein molecule.
The length of repeated units of amino acids in a peptide chain varies from 18-47.
While reading a peptide chain, the left end is called the N-terminal the amino o group, and the right end is called C-terminal which has the carboxylic group.