Write the structure of alanine at pH = 2 and pH = 10.

Explanation

Alanine exists as a Zwitter ion in aqueous solution as `""^(+)NH_(3)-underset(CH_(3))underset("| ")"CH"-COO^(-)`. In presence of acid `(pH=2)`, the basic `-COO^(-)` group accepta a proton and it exists as (I):
`""^(+)NH_(3)-underset(CH_(3))underset("| ")"CH"-COO^(-)overset(H^(+))rarr ""^(+)H_(3)N-underset("(I)")underset(CH_(3))underset("| ")"CH"-COOH`
In basic medium `(pH=10)`, the acidic group `-NH_(3)^(+)` gives a proton to the base and it exists as II:
`""^(+)NH_(3)-underset(CH_(3))underset("| ")"CH"-COO^(-)overset(OH^(-))rarrNH_(2)-underset("(II)")underset(CH_(3))underset("| ")"CH"-COO^(-)`