Download Exam 2 2016 Answers

MCB 4211, Fall 2016
Last, First name_____________________Student ID # ____________________
READ ALL THE CHOICES AND SELECT THE BEST
Seat No. _________
1. Why are people that carry CCR5 chemokine receptor mutations not found to have a serious
immune phenotype?
a. The complement cascade has three initiation points for activation.
b. Cytokines can have redundant and pleiotropic effects.
c. The MHC is always polymorphic.
d. Immunoglobulins can replace chemokines.
e. All of the above (A-D) are true.
2. The original discovery of TcR gene rearrangements showed that
a. VDJ rearrangements of the TcR beta chain and VJ rearrangements of the TcR
alpha chain were accomplished in T cells in the same way that VDJ
rearrangements in the immunoglobulin H chain and VJ rearrangements in the
immunoglobulin L chain happen in B cells.
b. The same gene segments were used in T and B cells for the rearrangement of antigen
binding receptors.
c. TcR Alpha and TcR beta chain were invariant in independently derived T cell clones.
d. All TcR rearrangements occur in the bone marrow
e. All of the above (A-D) are true.
3. Microbe associated molecular patterns (MAMP) are specifically important for
a. Adaptive immunity
b. Innate immune function
c. Cytotoxic T cell killing
d. The specific assembly of the membrane attack complex
e. Serine protease (granzyme) activity
4. Chemotactic cell movement can be stimulated by Zymosan activated serum (ZAS). The
molecular mechanism of this activation is
a. Via formylated peptide (e.g. fMLP) stimulation
b. Via MAMP action on Toll like receptors
c. Due to the interaction of complement following naturally occurring anti-yeast
antibodies in serum that bind to the killed yeast
d. All of the above(A-C) are correct
e. None of the above (A-D) are correct
5. Fractions of chicken soup can interfere with the migration of leukocytes in vitro. In the
Rennard et al. paper, why is this observation hard to connect to the in vivo antiinflammatory effects of chicken soup?
a. Leukocytes are not involved in inflammation
b. They found that chicken soup at the concentrations used was highly toxic in vitro
c. They found that chicken soup and its components activated a more profound
inflammation response in vitro
d. Leukocytes may not be exposed to the components of chicken soup in the form
used in the experiment since they must first pass through the gastrointestinal
tract when presented to a patient
e. None of the above (A-D) are true.
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MCB 4211, Fall 2016
Last, First name_____________________Student ID # ____________________
READ ALL THE CHOICES AND SELECT THE BEST
Seat No. _________
6. Expression of surface molecules can be detected by fluorescent microscopy using a
fluorescently labeled antibody that is specific for the surface molecule. In some cases,
those fluorescent molecules rearrange on the cell membrane to become distributed in
“patches” and “caps”. Why?
a. The antibody stimulates lipid peroxidation that can change plasma membrane density
b. The antibody can cross-link the surface molecules and slowly cause them to
aggregate as a consequence of the cross linking.
c. The antibody causes cell division
d. The antibody can cause surface molecules to become fluorescent themselves,
eliminating the need for antibody binding
e. All of the above (A-D) can have the observed effects on patching and capping.
7. In what cell type are MHC class II molecules expressed to stimulate adaptive immunity and
B cell production of antibody?
a. Macrophages
b. Tc cells
c. Polymorphonuclear neutrophils
d. Mast cells
e. Erythrocytes
8. The transporter of antigenic peptides (TAP) delivers peptide to the endoplasmic reticulum
where they interact with what molecule?
a. MHC class I
b. MHC class II
c. MHC class III
d. Tumor necrosis factor-alpha (TNF-a)
e. T cell receptor (TcR)
9. Signal transduction cascades that begin with ligand interacting with membrane receptor
typically include what molecular components?
a. Protein Tyrosine Kinases
b. Protein Tyrosine Phosphatases
c. Calcium responsive enzymes
d. Phospholipases (e.g. PLC)
e. All of the above (A-D) are correct.
10. Positive selection in the thymus is necessary to
a. Produce T cells that are anergic to antigenic stimuli
b. Produce T cells that can make cytokines
c. Produce T cells that can function in cold temperatures
d. Produce T cells that can respond to self MHC
e. Produce T cells that can respond to cytokines.
11. When most T cells reach the point of terminal differentiation in the thymus, they
a. Express either CD4 or CD8
b. Constitutively express cytokines
c. Are no longer expressing TcR molecules
d. Can be activated by MHC binding to TcR without a co-stimulatory molecule
e. All of the above (A-D) are true.
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MCB 4211, Fall 2016
Last, First name_____________________Student ID # ____________________
READ ALL THE CHOICES AND SELECT THE BEST
Seat No. _________
12. The immune synapse between antigen presenting cells (APC) and Th cells is stabilized by
a. CD8 interactions with the MHC
b. CD4 interactions with the MHC
c. TLR co-stimulation
d. Complement activation
e. Tc degranulation
13. Th1 and Th2 cells are differentiated by
a. The surface markers they express
b. The cytokines that they produce and the immune functions that they support or
suppress
c. The size and shape of their nuclei
d. The form of CD4 that they express
e. The CD8 that they express
14. The structure of MHC Class II consists of:
a. A complex of one α chain and one β2 microglobulin.
b. A complex of one α chain and one β chain, both of which contain
transmembrane domains.
c. One single polypeptide chain with two transmembrane domains.
d. One single polypeptide chain with one transmembrane domain.
e. A complex of two α chains and two β chains.
15. What is the purpose of negative selection?
a. To eliminate infected lymphocytes.
b. To eliminate B cells that do not produce sufficient amounts of antibody.
c. To eliminate cells that are potentially cancerous.
d. To eliminate cells with T cell receptors that bind too strongly to self-antigen.
e. To eliminate cells with T cell receptors that bind too weakly to foreign antigen
16. Which of the following is NOT a component of healthy gut-associated lymphoid tissue
(GALT)?
a. Peyer’s patches
b. Antigen-sampling M cells
c. Mesenteric lymph nodes
d. Activated neutrophils
e. These are all components of GALT.
17. Which of the following is a difference between MHC class I and MHC class II molecules?
a. The MHC I are the only molecules that present antigenic peptides to T cells
b. The MHC I are the only molecules that are expressed on antigen presenting cells
c. The MHC I are the only molecules that are synthesized and exported from the ER
d. The MHC I are the only molecules that are comprised of immunoglobulin domains
e. The MHC I are the only molecules that present antigenic peptides derived from
cytosolic proteins
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MCB 4211, Fall 2016
Last, First name_____________________Student ID # ____________________
READ ALL THE CHOICES AND SELECT THE BEST
Seat No. _________
18. There is a certain logic to the sequence of genes that are activated once a TcR has been
successfully engaged and a T cell has been stimulated. Which of the following is true of the
immediate genes that are activated?
a. These genes include those that encode transcription factors and enable an
amplification of the signaling cascades that occur upon stimulation.
b. These genes include genes that encode adhesion proteins so that the activated cells
will stay where they are stimulated.
c. These genes include genes that encode cytokines and their receptors so that the cells
can continue the initial stimulation with paracrine stimulations.
d. These genes include all of the gene sets listed in answers a to c.
e. None of the answers (A-D) are correct.
19. In the Zinkernagel and Doherty experiments, CTLs taken from a H-2k mouse infected with
CMV were NOT able to kill target cells that expressed which of the following?
a. H-2b MHC I proteins loaded with CMV derived peptides
b. H-2k MHC I proteins loaded with CMV derived peptides
c. H-2b MHC I proteins loaded with self-derived peptides
d. H-2k MHC I proteins loaded with self- derived peptides
e. a, c, and d are correct
20. Cytotoxic T cells kill by releasing the contents of their granules in the immediate vicinity of
their targets. What components are critical to CTL mediated killing?
a. activation of components of the complement cascade
b. release of perforin and serine proteases
c. production of toxic levels of reactive oxygen species
d. activation of endotoxin
e. the TAP proteins
21. Correct assembly of a functional MHC II protein loaded with an antigenic peptide requires
which of the following proteins or protein complexes:
a. TAP
b. calnexin
c. CLIP, Class II-associated invariant chain peptide
d. CD8
e. Papain
22. Positive and negative selections occur in the thymus in order to remove dysfunctional cells.
What kinds of cells do these processes remove?
a. cancer cells
b. pre-T cells
c. pre-B cells
d. CD4-,CD8- double negative cells
e. autoreactive T cells
23. Phospholipase C- (PLC-) indirectly influences the cytosolic concentration of what ion?
a. calcium
b. phosphorus
c. mercury
d. vanadium
e. sodium
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MCB 4211, Fall 2016
Last, First name_____________________Student ID # ____________________
READ ALL THE CHOICES AND SELECT THE BEST
Seat No. _________
24. Which of the following is not expressed by CD8+ T cells (also known as cytotoxic T
lymphocytes)?
a. MHC class I
b. MHC class II
c. CD3
d. CD28
e. ZAP70
25. What experimental result indicated to Peter Gorer that different strains of mice expressed
different allelic forms of MHC on cells?
a. The rejection of transplanted tissue in tail grafts
b. The ability to generate antibodies against poly GAGA or GTGT repeats
c. The ability of adsorbed rabbit anti-mouse erythrocyte antiserum to agglutinate
RBCs from some strains and not others
d. Immuno-precipitation of purified MHC proteins from hepatocytes
e. Radioactive probe hybridization to different locations on a southern blot
26. If the student sitting to your left was infected with the flu virus, how would viral peptides
be presented to that student’s TcR?
a. in the context of MHC Class I
b. in the context of MHC Class II
c. in the context of CD28
d. Viruses are not presented because they are cleared by the innate immune response
e. Both b and c are correct
27. Listeria monocytgenes is a bacterium that polymerizes actin tails to move around in the
cellular cytoplasm. What mechanism is most likely to eliminate Listeria-infected cells?
a. NK cells
b. ADCC cells
c. Antibody plus complement
d. Antibody-mediated agglutination
e. CTL-mediated killing
28. Calculate the amount of diversity in TcR antigen combining sites that is possible from the
following genetic segments.
TcR beta chain: 100 V, 10D and 10 J segments
TcR alpha chain: 10 V and 10 J segments
a. you cannot calculate diversity from this data
b. there are 140 possible permutations
c. there are 1,000,000 possible permutations
d. there are 1013 possible permutations
e. there are 106 possible permutations
29. Activation of a classical complement cascade results in lysis of a nearby membrane
because
a. there is a membrane insertion of the membrane attack complex that forms
b. there is activation of apoptotic cascades
c. there are changes in ionic distribution and hypotonic lysis
d. there is activation of serine proteases
e. all of the above (a-d) are true
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MCB 4211, Fall 2016
Last, First name_____________________Student ID # ____________________
READ ALL THE CHOICES AND SELECT THE BEST
Seat No. _________
30. Which of the cell types listed below can routinely present both endogenous and
exogenous antigen?
a. macrophages
b. pre-T cells
c. CD4+ cells
d. erythrocytes
e. neuronal cells
31. Recombination signal sequences (RSS) are one-turn and two-turn DNA sequences that
a. mark the ends of recombining immunoglobulin gene segments
b. initiate viral insertion into host DNA
c. are responsible for rearrangements of MHC genes to produce new polymorphisms
d. all of the above (a-c) are true
e. none of the above (a-c) are true
32. During positive selection in the thymus, what cellular function is activated to eliminate the
95-98% of the cells that fail the selection process?
a. These cells acidify their environment
b. These cells accumulate in the lymph nodes
c. These cells undergo apoptosis
d. These cells aggregate around the high endothelial veinules (HEV)
e. These cells abrogate TcR/MHC interactions
33. Why is a live virus thought to elicit both cell mediated immunity and humoral immunity
while killed virus only provokes a humoral response?
a. viral antigens stimulate all immune cells
b. proliferating viruses do not kill macrophages
c. proliferating virus can activate the cytotoxic T cells to kill the infected target
while live and dead viral particles released from host cells activate antibody
production
d. live virus is never an effective immunogen
e. humoral responses do not recognize live viruses
34. Food proteins are exposed to the immune system during their passage through the gut.
What mechanism is used to prevent food allergies in most healthy individuals?
a. Selection for cells that do not recognize food antigens during thymus differentiation of
T cells
b. Selection for cells that do not recognize food antigens during differentiation in the
Bursal equivalent.
c. Anergy, deletion of responsive T cells and the generation of regulatory T cells in
the gut-associated immune tissues
d. All of the above (A-C) operate to prevent food allergies.
e. None of the above (A-D) operate to prevent food allergies.
35. What adaptive immune component is important in managing microbiome composition on
mucosal surfaces?
a. Secreted IgA
b. Intracellular IgE
c. Serine proteases
d. Toll-like receptors
e. complement
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MCB 4211, Fall 2016
Last, First name_____________________Student ID # ____________________
READ ALL THE CHOICES AND SELECT THE BEST
Seat No. _________
Short answer. Provide a phrase or sentence to answer the questions posed below (questions
36-40).
36. What common molecular structure is shared by antibody, the T cell receptor, and many other
markers expressed on leukocyte plasma membranes?
Immunoglobulin gene segments
37. What significant changes to the genetic composition of offspring occur as a result of crossing
over within an inversion in the parent’s germ (sperm or egg) cells?
Offspring may inherit chromosomes with either extra or deleted segments; can lead to
addition or deletion of genes
38. When Tc (CTL) cells engage a tumor target cell, what morphological change happens in the Tc
cells before they can kill the target cell?
Tight binding of CTL to target cell, granule redistribution, release of granule contents after
vesicles fuse with plasma membrane
39. Why does an attenuated (weakened) virus usually serve as a better vaccine material than killed
virus?
Live attenuated vaccine- activates humoral and cellular immunity; slower and prolonged
antigen exposure
Killed vaccine- stimulates mostly humoral response
40. In the gastrointestinal tract, what is the name of the small aggregations of leukocytes that are
responsible for both antigenic sampling of the intestinal lumen, and the collection of leukocytes that
subsequently drain to the mesenteric lymph node?
Peyer’s patches
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