An amino acid is made up of four groups bonded to a central carbon atom. These groups include a hydrogen atom, a carboxyl group, an amine group and a R group. The R group differs for each amino acid. A peptide bond forms between two amino acids in a condensation reaction. The bond forms between the carboxyl group of one amino acid and the amine group of the other. This is a condensation reaction, where two molecules react to form one, joined by a bond and includes the removal of water. The bond is called a peptide bond.