a. Hypoxanthine was present in the media. MCB 4211, Fall 2018, Practice Exam 1 Last, First name Student ID # Seat No.

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1 MCB 4211, Fall 2018, Practice Exam 1 Last, First name Student ID # Seat No. ***NOTE: Exam will have 40 multiple choice questions. READ ALL THE CHOICES AND SELECT THE BEST 1. Which of the following characteristics differentiates between the five immunoglobulin classes? a. They are coded by different families of genes. b. They differ in the antigenic shape of their antigen binding pockets. c. Some classes of antibody do not bind antigen. d. They contain different amino acid sequences in their light chains. e. They contain different amino acid sequences in the heavy chains. 2. Which of the following is NOT one of the weak forces involved in antibody-antigen interactions? a. Covalent bonds b. Hydrogen bonds c. Hydrophobic interactions d. Ionic/electrostatic bonding e. Van der Waals interactions 3. What does the Law of Mass Action tell you about an antibody and antigen? a. The types of molecular forces involved in antibody-antigen interaction. b. The isotype class of the antibody. c. The subclass of the antibody. d. The strength of the interaction between the antibody and the antigen. e. The molecular weight of the antibody. 4. In which of the following tissue(s) would you expect to find lymphocytes that are not normally exposed to foreign antigen? a. Thymus b. Tonsils c. Spleen d. Lymph nodes e. All of the above 5. Hozumi and Tonegawa s experiment showed that a deletion within the Immunoglobulin light chain gene was detected by the disappearance of a restriction endonuclease site. Why was it important to match the strain providing the myeloma DNA to the strain providing the embryonic DNA for the comparison of VC probe hybridization patterns? a. Mismatched strains would possibly result in differing patterns in the restriction endonuclease cut pattern due to allelic differences. b. Mismatching strains would mean that the electrophoresis conditions to separate the DNA would have to be altered to fit the strain. c. Embryos from different strains develop differently. d. Mismatched strains might result in a strain that does not develop B cell tumors. e. All of the above are true. 6. In Kohler and Milstein s work to produce an immortalized anti-sheep erythrocyte monoclonal antibody, they hybridized normal splenic B cells from a mouse that had been immunized with sheep erythrocytes and a B cell myeloma. Why was it necessary to use a myeloma that was mutant for the HGPRT gene? a. Hypoxanthine was present in the media. 1

2 b. Without the HGPRT gene, the DNA salvage pathway is defective, and thus unfused myeloma cells that are cultured in aminopterin (which blocks the de novo DNA synthesis pathway) cannot synthesize DNA and die c. Without the HGPRT gene, the myeloma cells will not be able to contribute to the synthesis of antibody. d. Without the HGPRT gene, the cells are unable to fuse in the presence of PEG fusogen, and thus do not contribute to hybridoma formation e. Without the HGPRT gene, the myeloma cells will be immortal. 7. Two mice from a congenic strain differ from one another by: a. A single locus b. A target gene and surrounding passenger loci c. Disease phenotype d. The ability to develop mature T cells e. They are genetically identical 8. Which of the following is NOT an advantage of using mice as a model organism? a. Mice are relatively inexpensive to maintain b. Mice breed very quickly c. Mice can be inbred to reduce genetic heterogeneity d. They do not develop spontaneous mutations e. Mice are physiologically similar to humans 9. Which of the following statements is FALSE regarding immunogens? a. They are recognized as foreign by the T cell receptor. b. They are recognized as foreign by the B cell receptor c. All antigens are immunogens. d. They must be of a certain structural complexity. e. All of the above statements are true. 10. What is an epitope? a. An antigen that is too small to be recognized by a T or B cell receptor b. A large protein that allows an antigen to meet the structural requirements to elicit an immune response c. The region of an antigen that is recognized by an antibody d. A conjugate of an antigen and a carrier protein e. A large synthetic polymer 11. A rabbit is immunized with Antigen X conjugated to Carrier Protein Y. After an appropriate amount of time, antiserum is collected from the rabbit. If Carrier Protein Y is mixed with the antiserum, would you observe precipitation? a. No, the antiserum only contains antibodies that recognize Antigen X which are unable to recognize Carrier Protein Y. b. No, Carrier Protein Y is not structurally complex enough to be recognized by the B cell receptor. c. No, the antibodies found in the rabbit s antiserum only recognize the Antigen X:Carrier Protein Y conjugate. d. Yes, the rabbit antiserum contains antibodies that recognize Antigen X as well as antibodies that recognize Carrier Protein Y. e. Yes, the antibodies that recognize epitopes on Antigen X will likely cross-react with Carrier Protein Y due to their structural similarities. 2

3 Questions relate to the results of the precipitation reactions described in the table below. The number of + s indicates the size of the immunoprecipitate (more + s mean more precipitation). 0 indicates no precipitation. Antiserum used in the immunoprecipitation reaction Antigens used in the immunoprecipitation Hapten A-protein conjugate Hapten B-protein conjugate Anti-Hapten A Anti- Hapten B Anti- Hapten C Anti- Hapten D +++ (1) 0 (2) + (3) 0 (4) 0 (5) +++ (6) ++ (7) 0 (8) 12. Which of the above reactions represent interactions of antibodies in the antiserum with their cognate antigen? a. 1 only b. 6 only c. 1 and 6 d. 2, 4, 5, and 8 e. 3 and Which of the above reactions demonstrate cross-reactivity of the antibodies in the antiserum? a. 1 only b. 6 only c. 1 and 6 d. 2, 4, 5, and 8 e. 3 and What would this table look like if the animals were immunized with haptens that were NOT conjugated to carrier protein? a. Anti-A antiserum would bind to hapten B b. Anti-D antiserum would now bind to hapten C c. All of the boxes would have a 0 in them d. All of the boxes would probably have a +++ in them e. None of the above 15. When multiple antibody subunits of the same isotype are assembled by the B cell and secreted as dimers or pentamers, what holds them together? a. Fab fragments b. Antigen binding pockets c. J chains d. Hydrogen bonds e. Ionic bonds (salt bridges) 16. What is the result of proteolytic digestion with papain at the hinge region of an antibody? a. 2 Fab fragments and an Fc fragment b. 1 F(ab )2 fragment and an Fc fragment c. 1 F(ab )2 fragment and peptides d. 2 heavy chains only e. 2 heavy chains and 2 light chains 3

4 17. An IgG antibody is exposed to 2-mercaptoethanol, a reducing agent that disrupts disulfide bridges. What are the resulting fragments? a. 2 Fab fragments and an Fc fragment b. 1 F(ab )2 fragment and an Fc fragment c. 1 F(ab )2 fragment and peptides d. 2 heavy chains only e. 2 heavy chains and 2 light chains 18. Which regions of the antibody form the antigen combining site? a. The constant and variable regions of the heavy chains (CH and VH) b. The constant and variable regions of the light chains (CL and VL) c. The variable regions of the heavy and light chain (VH and VL) d. The entire light chain (CL and VL) plus the variable region and constant region 1 of the heavy chain (CH1 and VH) e. All regions of the antibody are required for antigen binding 19. Which of the following would NOT be a beneficial effect of an adjuvant? a. Activation of phagocytosis b. Non-specific activation of lymphocytes c. Gradual release of antigen to prolong exposure d. Activation of mast cell degranulation e. These are all (A-D) beneficial effects of adjuvants. 20. Which of the following contribute to the differences in total molecular weight that distinguishes different isotypes (classes) of antibodies? a. The numbers of C domains present in the heavy chain b. J chains that hold oligomerized antibodies together c. Post-translational modifications such as glycosylation d. A, B, and C e. None of the above 21. Antibody allotypes refer to: a. The type of heavy chain that antibody harbors b. The sequence of the antigen binding pocket c. The oligomerization state of the antibody d. Antigenic dissimilarities between individuals of the same species e. Antigenic dissimilarities between individuals of different species 22. Equilibrium dialysis is an experimental tool that can be used to calculate what type of information about an antibody? a. The strength of its interaction with antigen b. Its molecular weight c. Its solubility at equilibrium d. The types if intermolecular forces contributing to antibody:antigen interactions e. The isotype of the antibody 23. Which of these terms best describes the unique antigenic shape of the antibody s antigen combining site? a. Idiotype b. Allotype c. Isotype d. Paratope e. Isotope 4

5 24. Which of the following is NOT a function of antibodies? a. Precipitation and agglutination b. Complement fixation c. Opsonization to mediate phagocytosis d. Antibody-dependent cell-mediated cytotoxicity e. These are all functions of antibodies 25. In flow cytometry, what information does the forward angle light scatter provide? a. The relative size of the cell b. The internal complexity of the cell c. Expression of certain surface markers d. The identity of the cell based on surface marker expression e. Whether or not the cell is producing antibody 26. Which of the following methods is BEST for measuring the concentration of circulating antibodies in the serum sample of a patient? a. Flow cytometry b. Immunohistochemistry c. Equilibrium dialysis d. Enzyme-linked immunosorbent assay (ELISA) e. None of these assays are capable of measuring antibody in serum 27. In the Kohler and Milstein experiment, the selection of cells making anti-srbc antibodies was done with soft agar clones that were capable of a. Crosslinking the srbc b. Secreting antibody that could activate complement and lyse the srbc c. Secreting complement d. Surviving with hundreds of extra chromosomes e. Secreting cytokines 28. What experimental result identified the isotype of the anti-sheep erythrocyte antibody in the Kohler and Milstein paper? a. Anti- antibody modified the diffusion of the anti-sheep erythrocyte antibody and its ability to lyse some of the sheep erythrocytes b. Isoelectric focusing separated the anti- sheep erythrocyte antibodies from those contributed by the myeloma parental cell and identified the isotype of the anti- sheep erythrocyte antibodies c. Anti-IgG antibody prevented fusion of the hybridoma cells d. A and B are both true e. All of the above are true 29. How can you calculate the percentage of tissue grafts that will succeed when that tissue is grafted from an inbred mouse to the F2 generation mice from a mating of that inbred mouse with a second inbred mouse strain? a. The frequency of success is the inverse of (3/4) n where n is the number of genes that control antibody production b. The frequency of success is equal to (3/4) n where n is the number of engrafted individuals c. The frequency of success is proportional to the size of the graft d. The frequency of success is equal to (3/4) n, where n is the number of segregating genes that contribute to graft antigen display that is different to the recipient e. None of the above are true 5

6 30. Name the five isotypes of antibody by the heavy chains they have e. CD4, CD8, IL10, C, and IFN- 6