19-1 Structures of Amino Acids Amino acids exist in aqueous solution primarily in the form of a dipolar ion,or zwitterion Zwitterion German zwitter,,meaning“hybrid” A neutral dipolar molecule in which the positive and negative charges are not adjacent H3C. → H3C OH H2>N H H3N (uncharged) (zwitterion) Alanine Amino acids exist in aqueous solution primarily in the form of a dipolar ion, or zwitterion Zwitterion ▪ German zwitter, meaning “hybrid” ▪ A neutral dipolar molecule in which the positive and negative charges are not adjacent 19-1 Structures of Amino Acids