Multiple Choice Questions on Protein Function

1. A prosthetic group of a protein is a non-protein structure that is:
a) a ligand of the protein.
b) a part of the secondary structure of the protein.
c) a substrate of the protein.
d) permanently associated with the protein.

2. In the binding of oxygen to myoglobin, the relationship between the concentration of oxygen and the fraction of binding sites occupied can best be described as:
a) hyperbolic.
b) linear with a negative slope.
c) linear with a positive slope.
d) sigmoidal.

3. Myoglobin and the subunits of hemoglobin have:
Myoglobin and Hemoglobin
a) no obvious structural relationship.
b) very different primary and tertiary structures.
c) very similar primary and tertiary structures.
d) very similar tertiary structures, but different primary structures.


4. In hemoglobin, the transition from T state to R state (low to high affinity) is triggered by:
a) Fe2+ binding.
b) heme binding.
c) oxygen binding.
d) subunit association.

5. Which of the following is not correct concerning cooperative binding of a ligand to a protein?
a) It is usually a form of allosteric interaction.
b) It is usually associated with proteins with multiple subunits.
c) It rarely occurs in enzymes.
d) It results in a nonlinear Hill Plot.

6. The fundamental cause of sickle-cell disease is a change in the structure of:
a) blood.
b) capillaries.
c) hemoglobin.
d) red cells.

7. The proteins of the Major Histocompatibility Complex (MHC) bind and display:
a) antigen fragments.
b) B cell fragments.
c) immunoglobin fragments.
d) macrophage fragments.

8. A monoclonal antibody differs from a polyclonal antibody in that monoclonal antibodies:
a) are labeled with chemicals that can be visualized.
b) are produced by cells from the same organism that produced the antigen.
c) are synthesized by a population of identical, or “cloned,” cells.
d) are synthesized only in living organisms.

9. The predominant structural feature in myosin molecules is:
a) a b structure.
b) an a helix.
c) the Fab domain.
d) the light chain.

10. During muscle contraction, hydrolysis of ATP results in a change in the:
a) conformation of actin.
b) conformation of myosin.
c) structure of the myofibrils.
d) structure of the sarcoplasmic reticulum.

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Answers
1. d) permanently associated with the protein.
2. A) hyperbolic.
3. d) very similar tertiary structures, but different primary structures
4. c) oxygen binding.
5. c) It rarely occurs in enzymes.
6.  c) hemoglobin.
7. a) antigen fragments.
8. c) are synthesized by a population of identical, or “cloned,” cells.
9. b) an a helix.
10. B) conformation of myosin.
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