The monomers of proteins are amino acids. Proteins are composed of long chains of amino acids linked together by peptide bonds, forming polypeptide chains that fold into functional three-dimensional structures

. Each amino acid has a common fundamental structure consisting of:

• A central carbon atom (alpha carbon)
• An amino group (-NH2)
• A carboxyl group (-COOH)
• A hydrogen atom
• A distinctive side chain or R group that varies among different amino acids and determines their specific properties

There are 20 standard amino acids that serve as the building blocks for all proteins in living organisms. The sequence and composition of these amino acids in a protein define its primary structure and ultimately influence its function

. In summary, amino acids are the monomeric units that polymerize to form proteins.