Write the structure of the ionized form of phenylalanine

Amino Acids undergo a kind of acid base reaction within a molecule. The Amino group acts as a base and accepts proton from Carboxylic functional group resulting in formation of Ammonium with positive charge and a negative charge on Carboxylate. Such molecules containing both positive and negative charges are called as Zwittor Ions. Phenylalanine both in Un-ionized and Ionized form is shown below,