Serine $left(mathrm{C}_{3} mathrm{H}_{7} mathrm{NO}_{3} ight)$ is a nonessential amino acid that plays an important role in the

Serine $\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{NO}_{3}\right)$ is a nonessential amino acid that plays an important role in the catalytic function of many enzymes. The dissociation constants for serine are $\mathrm{p} K_{a 1}=2.21$ and $\mathrm{p} K_{a 2}=9.15$.

(a) Plot the charge of this amino acid as a function of $\mathrm{pH}$.

(b) Calculate the isoelectric point of serine.