Amino acids, peptides, and proteins

Question 1

1. Which of the following amino acids participates in formation of new polypeptide chains?

a. Desmosine
b. Ornithine
c. Histidine
d. Taurine

Answer 1

c. Histidine

Question 2

2. Which of the following amino acids is the most hydrophobic at physiologic pH?
   a. Glutamate
   b. Lysine
   c. Isoleucine
   d. Threonine

Answer 2

c. Isoleucine

Question 3

3. The pH at which a molecule such as a protein has a net
   charge of zero is referred to as the:

a. isoelectric point.
b. dissociation constant.
c. isosbestic point.
d. solubility point.

Answer 3

a. isoelectric point.

Question 4

4. A paraprotein is a:
   a. membrane-bound protein.
   b. denatured/unfolded protein.
   c. protein-prosthetic group.
   d. monoclonal immunoglobulin.

Answer 4

d. monoclonal immunoglobulin.

Question 5

5. Which of the following is a ketogenic amino acid?
   a. Glycine
   b. Leucine
   c. Glutamate
   d. Proline

Answer 5

b. Leucine

Question 6

6. Which of the following is a positive acute-phase reactant?
   a. Transferrin
   b. Albumin
   c. Ferritin
   d. Prealbumin

Answer 6

c. Ferritin

Question 7

7. Covalent modification of proteins with ubiquitin leads
   to:
   a. membrane localization.
   b. catabolism/destruction.
   c. enhanced activity.
   d. nuclear localization

Answer 7

b. catabolism/destruction

Question 8

8. The plasma protein that serves to transport a large number of compounds including bilirubin, calcium, drugs,
   and free fatty acids is:
   a. prealbumin.
   b. ceruloplasmin.
   c. haptoglobin.
   d. albumin.

Answer 8

d. albumin.

Question 9

9. α1 Antitrypsin inhibits which class of protease?
   a. Metalloproteases
   b. Aspartyl proteases
   c. Cysteinyl proteases
   d. Serine proteases

Answer 9

d. Serine proteases

Question 10

10. The most abundant circulating immunoglobulin in adult
    serum is:
    a. IgA.
    b. IgD.
    c. IgG.
    d. IgM.

Answer 10

c. IgG.