The amino acid which is basic in nature is

The functional group which is found in amino acid is

Find the isoelectric point $(pI)$ of the given amino acid.
$CH_3-CH(NH_3^+)-CO_2H, \ pK_a = 2.2, \ pK_b = 4.4$

The number of essential and non-essential amino acids from the following list respectively is:
Val,Gly,Leu,Lys,Pro,Ser

Protein found in a biological system with a unique three-dimensional structure and biological activity is called a native protein. When a protein in its native form is subjected to a physical change like a change in temperature or a chemical change like a change in $pH$,denaturation of proteins takes place. Explain the cause.

For an amino acid,the ionization constant for the carboxyl group is $pK_{a_1} = 2.34$ and for the ammonium ion is $pK_{a_2} = 9.6$. At what $pH$ will the isoelectric point of the amino acid be?