1. Which of the following properties does not apply to MHC class I molecules?

A. Heterodimeric cell-surface glycoproteins
B. Expression on B cells and macrophages
C. Co-dominant expression
D. Bind peptides derived predominantly from extracellular (exogenous) antigens
E. "Restrict" CD8+ (cytotoxic) T cells

2. Which of the following does not apply to MHC class II molecules?

A. Heterodimeric cell-surface glycoproteins
B. Expression on B cells and macrophages
C. HLA-DP, -DQ, and DR
D. Genetically associated with certain autoimmune diseases
E. Contain immunoglobulin-like peptide-binding domain

3. 'TAP' proteins are required for

A. normal cell-surface expression of MHC class I molecules.
B. presentation of most protein antigens to CD8+ T cells.
C. transport of most peptides derived from foreign antigens into endoplasmic reticulum.
D. transport of most peptides derived from "self" proteins into endoplasmic reticulum
E. all of the above

4. The number of different MHC class I molecules that will be expressed on all nucleated cells of a normal, MHC heterozygous individual will be

A. 0
B. 3
C. 6
D. 9
E. 12

5. Chemical agents such as chloroquine or NH₄Cl, which neutralize the pH of acidified intracellular compartments, would most likely

A. inhibit the class I, but not the class II, antigen processing pathway
B. inhibit the class II, but not the class I, antigen processing pathway
C. inhibit both the class I and class II antigen processing pathways.
D. inhibit neither the class I nor class II antigen processing pathways.
E. inhibit B cell but not T cell responses to foreign antigens.

6. Bacterial movement towards nutrients is called

A. phototaxis.
B. chemotaxis.
C. magnetotaxis.
D. aerotaxis.
E. thermotaxis.

7. Streptomycin, gentamicin, and tobramycin are members of which group of antibiotics?

A. Aminoglycosides
B. Beta-lactams
C. Polyenes
D. Quinolones
E. Tetracyclines

8. The presence of one million organisms in a stool specimen is in and of itself

A. indicative of clinical disease.
B. of diagnostic significance.
C. diagnostically insignificant.
D. cause for immediate antibiotic treatment.
E. None of the above.

9. Bacterial lipopolysaccharides (endotoxins) activate a multitude of host defense reactions. Large amounts of LPS in the blood often lead to septic shock. With what kind of infections is LPS associated?

A. Gram positive species
B. Gram negative species
C. Both of the above
D. Intracellular parasites
E. Viral septicemias

A. They can be used to prepare competent cells.
B. They digest DNA at specific nucleotide sequences.
C. They can produce blunt or overhanging ends.
D. They are used by bacteria to degrade foreign DNA.
E. They are names for the organisms from they were originally isolated.

A. Feedback inhibition of various metabolic pathways allow the organism to halt biosynthesis of a product if it becomes available in the growth environment.
B. Feedback inhibition involves binding of the product to the last enzyme in the pathway and thus blocking further synthesis.
C. Attenuation is a mechanisms employed to control enzyme syntheses.
D. Stalling of ribosomes at different sites on a small RNA transcript is an important event in the process of attenuation.
E. A mechanisms used to respond to exogenously added substrates is the utilization of repressors and inducers to regulate the transcription of enzymes for some metabolic pathways.

The following questions can be answered with one or two words or a sentence.

12. What is the major role of pili?

___________________________________

13. Define the term, conjugation.

_____________________________________________________________

_____________________________________________________________

Answers:
1. D
2. E
3. E
4. C
5. B
6. B
7. A
8. C
9. B
10. A
11. B
12. Bacterial adherence
13. Conjugation is the unidirectional exchange of genetic information from one bacterium (donor) to another bacterium (recipient); involves direct cell to cell contact.