Answer:
Amino acids.
Step-by-step explanation:
Polypeptide is a primary structure of a protein. It is formed by joining amino acids by peptide bonds in a linear sequence. In other words, polypeptide is a polymer of amino acids held by peptide bonds. A peptide bond is formed when the carboxylic group one amino acid reacts with an amino group of another amino acid. The amino group loses a hydrogen atom (H) and the carboxylic group loses a hydroxyl (OH) to form water (H2O), when the peptide bond is formed. Thus, amino acids are the monomers of a polypeptide.