Give reason for the following: On electrolysis in acidic solution, amino acids migrate towards cathode while in alkaline solution these migrate towards anode. ii) The mono amine monocarboxylic acids have two `p^K` values.

Explanation

i) Amino acids have zwitter ionic structure. In presence of strong acids they exist as cations I and hence on electrolysis. They migrate towards cathode.
FIGURE
But in presence of alkalies, the amino acids exist as anions (II) and thus on electrolysis, these migrate towards anode.
FIGURE
ii) A mono aminomonocarboxylic acid exists as a dipolar ion. 'H_3 ~N^+-CH_i-CO overlineO'
In this 'NH_3^+' acts as acid and 'COO' acts as base. Thus monoamino monocarboxylic acid can aci both as an acid and as a base. These acids have two 'p^k' values one as an ncid and other as a base.