Answer: the carboxyl group (COOH) of one amino acid reacts with the amino group (NH2) of another amino acid.
Step-by-step explanation:
This reaction results in the formation of a covalent bond between the two amino acids, with the release of a water molecule (H2O) in a process called a condensation reaction or dehydration synthesis. The resulting bond between the amino acids is called a peptide bond, and the resulting molecule is a dipeptide. As more amino acids join through peptide bonds, a polypeptide chain is formed, which can eventually fold and function as a protein.