bond connects nitrogen one amino acid 's amino group carbon 's carboxylic acid group resulting molecule called ' 'dipeptide'' short stretches amino acids usually fewer thirty called ''peptides'' polypeptides longer stretches merit title ''proteins'' example important blood serum protein albumin contains amino acid residues ref name metzler metzler p ref generic amino acids neutral form exist physiologically joined together dipeptide schematic hemoglobin red blue ribbons represent protein globin green
Natural science Biology Biochemistry