11. Which of the following pairs of amino acids would carry a negative charge on their side chain at pH 8.0?

A. Asparagine & Glutamine
B. Leucine & Glycine
C. Histidine & Lysine
D. Aspartate & Glutamate

12. In a polypeptide average mass of an amino acid residue is

A. 110 daltons
B. 118 daltons
C. 80 daltons
D. 150 daltons

13. Which pair of amino acids absorbs the most UV light at 280 nm?

A. Threonine & Histidine
B. Trp & Tyrosine
C. Cystein & Asparagine
D. Phenylalnine & Proline

14. Which of the following is a nonstandard amino acid?

A. Cysteine
B. Isoleucine
C. Hydroxyproline
D. Histidine

15. Which of the following is an essential amino acid?

A. Tryptophan
B. Methionine
C. Lysine
D. All of these