As we know that there exist 20 amino acids as a residue in proteins. We now turn to polymers of amino acids,  peptides, and  proteins . They exist as a long chain of amino acids linked up together or maybe three or four amino acids are linked together. Biologically occurring polypeptides vary in size from small to very large. So let's get a deeper insight into it. # Peptides are chains of amino acids  Do you know that formation of peptide bonds is a type of condensation reaction? Two Amino acid molecules are covalently joined via an amide linkage, termed  peptide linkage of the peptide bond . Such bonds are formed by the removal of water (dehydration) from the alpha carboxyl group and alpha-amino group of other amino acids. When three amino acids are linked together by a peptide bond, they get two peptide bonds and are termed tripeptides. Similarly, four amino acids will form tetrapeptide and have three peptide bonds. This will goes on and so forth to form a polypeptide.  Polypept