Write a note on amino acids.

(N/A) Amino acids are organic compounds containing both an amino group $(-NH_2)$ and a carboxyl group $(-COOH)$ attached to the same carbon atom,known as the $\alpha$-carbon.
They are the building blocks of proteins.
The general structure of an $\alpha$-amino acid is $R-CH(NH_2)-COOH$.
In aqueous solution,the carboxyl group can lose a proton and the amino group can accept a proton,giving rise to a dipolar ion known as a zwitterion.
This is represented as: $R-CH(NH_2)-COOH \rightleftharpoons R-CH(NH_3^+)-COO^-$.
Except for glycine,all naturally occurring $\alpha$-amino acids are optically active.