An optically active amino acid (A) having molecular formula `C_(5)H_(11)NO_(2)` can exist in three forms depending upon the pH of the medium. Write the structure of (A) in aqueous medium. What are such ions called ? In which medium the cationic and the anionic forms of the amino acid (A) exist and towards which electrode they migrate in an electric field?

Explanation

The optically active amino acid (A) is valine `Me_(2)CH - CH (NH_(2)) - COOH`. Depending upon the pH of medium, valine can exist in the following three forms (I-III):

In aqueous medium, valine exists as a zwitterion (II). In acidic medium, it will exist as (I) and in an electric field, it will migrate towards cathode. In basic medium, it will exist as (IIII) and in an electric field, it will migrate towards anode