1A.If you were to have a mythical amino acid based on glutamic acid, but one in which the hydrogen that is attached to the -carbon were replaced by another amino group, what would be the predominant form of this amino acid at pH 12 if the pK_a value were 10 for the unique amino group? SELECT ALL THAT APPLY (more than one answer)

The amino acid carries a negative 4 charge.

The amino groups are in the form -NH^-.

The amino acid carries a negative 2 charge.

Both of the carboxyl groups are deprotonated.

Both of the amino groups are deprotonated.

1B. Draw the possible products formed when the amino acids, methionine and serine, react to form a peptide bond.

1C. Based on the pK_a values for the 20 amino acids commonly found in proteins, is there any amino acid that could serve as a buffer at pH 4? (Yes/No) If so, state which one? (If not, leave blank.)

1D. Indicate which of the amino acid residues in the following peptide sequence contains a group that has a negative charge for its most likely charge state at pH 10.

Cys-Pro-Gln-Asp-Arg-Phe-Ser-Lys-Val

(If none of the amino acids fit the criterion, select "none".)