How is a dipeptide defined?

A dipeptide is specifically defined as a molecule consisting of two amino acids linked by a peptide bond. This occurs when the carboxyl group of one amino acid reacts with the amino group of another, resulting in the release of a water molecule in a condensation reaction. This definition distinguishes dipeptides from other forms of peptides or protein structures.

For example, a tripeptide would consist of three amino acids, and a polypeptide refers to a longer chain of amino acids. The fundamental unit of a protein is made up of one or multiple amino acids, but when only two are combined, it accurately forms a dipeptide. A single amino acid unit represents a single building block and does not constitute a peptide structure. Therefore, the correct definition of a dipeptide as two amino acids bonded together is clear and precise.