The reaction that allows amino acids to become linked together is called dehydration synthesis.

Here's how it works:

1. Monomers (amino acids) approach each other. The carboxyl group (-COOH) of one amino acid aligns with the amino group (-NH2) of another amino acid.

2. Water molecule is removed: A water molecule is released as a hydrogen atom (H) from the amino group and a hydroxyl group (OH) from the carboxyl group are removed.

3. Peptide bond formation: The carbon atom from the carboxyl group and the nitrogen atom from the amino group form a strong covalent bond called a peptide bond.

This process repeats, linking multiple amino acids together to form a polypeptide chain, which eventually folds into a protein.

Important Note: This reaction requires energy and is typically catalyzed by enzymes called ribosomes in the process of protein synthesis.