Exam II - Spring 2008 (KEY) - NAME: NETWORK ID: MCB 408...

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1 NAME: NETWORK ID: MCB 408 Exam II March 6, 2008 Multiple Choice: Choose the BEST answer from the choices A – D. Please read all questions carefully! 1. In the figure below, the x-axis refers to: A. Variability B. Amino acid residue position of a variable region C. Number of variable region genes sequenced D. Number of alleles known for this gene 2. From the figure above, I would predict that two variable regions would have the greatest probability of differing at residue: A. 20 B. 40 C. 80 D. 100 3. Among different V H regions, which CDR has the most variability in the length of the loop? A. CDR1 B. CDR2 C. CDR3 D. Can not tell from the information given
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2 4. A RAG-1 knockout (homozygous) mouse would lack: A. B cells B. T cells C. B cells and T cells D. Antigen presenting cells 5. The 12/23 base pair “rule” for a RSS allows the recombination enzymes to: A. Recognize the heptamer-nonamer sequence by docking on the same side of the helical DNA B. Recognize the coding gene segments C. Cleave at the heptamer-nonamer junction, within the 12/23 sequence D. Cleave the DNA within the nonamer sequence 6. The D gene segment of heavy chains is about base pair(s) long A. 1 B. 10 C. 100 D. 1000 7. You have discovered a specific enzyme called Mut-1 that is critical for targeting V region genes for mutations. What would be the best strategy to determine the effect of this gene on antibody affinity? A. Culture B cells with siRNA for Mut-1, produce hybridomas, purify antibodies, measure affinities B. Culture B cells with siRNA for Mut-1, purify secreted antibodies, measure affinities C. Generate Mut-1 knockout mouse, produce hybridomas, purify antibodies, measure affinities D. Generate Mut-1 knockout mouse, purify secreted antibodies, measure affinities 8. Referring to the question above, what cell types would you expect to express transcripts for Mut-1? A. B cells B. Plasma cells C. T cells D. All of the above
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3 9. In the DNA accessibility model of gene rearrangement, it has been proposed that transcription of an unrearranged V gene is necessary to “open” the DNA so that it is accessible for RAG enzymes to operate at RSS regions. Based on this model, why do you think that T cells have not rearranged their immunoglobulin (Ig) genes, even though they express RAG-1 and RAG-2? A. The splicing sites between the V and the D (or J) gene segments differ between TCR and Ig genes B. The promoters of TCR V genes differ from those of Ig V genes C. There is transcription of unrearranged Ig V genes in T cells, but not unrearranged TCR V genes D. T cells lack hepatmer-nonamer sequences 10. If you had to choose one, which of the following cells types do you believe is the most critical “bridge” between innate and adaptive immunity? A.
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This note was uploaded on 02/17/2009 for the course MCB 408 taught by Professor Siechen during the Spring '08 term at University of Illinois, Urbana Champaign.

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Exam II - Spring 2008 (KEY) - NAME: NETWORK ID: MCB 408...

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