# A protein is phosphorylated at a serine residue. A phosphomimic mutant of the protien can be generated by substituting that serine with?- a. Glycine b. Alanine c. Aspartate d. Threonine

Phosphorylation basically introduces a negative charge on the suraface of the protein (actually 2, but who is counting?!). $P {O}_{4}$ when bound to Serine will have 2 negative charges. Anyway, if you want to mimic this phospho group, you'd substitute a negatively charged amino acid at this position, and that one would be Aspartic Acid (aspartate) or glutamic Acid (glutamate).