mcb150-fa10-mt1-Astar Winoto-soln

mcb150-fa10-mt1-Astar Winoto-soln - Fall 2010 MCB 150...

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Unformatted text preview: Fall 2010 MCB 150 Midterm1 Name (last, first): Page 1 Please use PEN only. Each page (total of 4 pages) must have your name on the top . 1 a) (4 pts) What is the main difference between a lamprey variable lymphocyte receptors (VLR) and a human lymphocyte receptor? Lamprey VLRs use Leucine Rich Repeats (LRR) while the human lymphocyte receptors use Ig domains to detect antigens. b) (4pts) how is diversity generated in lamprey VLRs during development (please be specific)? From the paper's abstract: "To generate diversity, the single lamprey VLR locus contains a large bank of diverse LRR cassettes that are available for insertion into an incomplete germline VLR gene" 2) (8 pts) The human/mouse immune system can clear a virus that infect dendritic cells BETTER than a virus that infects skin fibroblast cells. Why is this? Dendritic cells are APC and express the B7 molecules that can provide the 2 nd signals to directly stimulate killer T cells. Skin fibroblast cells don't have B7 and need to recruit T cell help to activate the killer T cells. Acceptable answer: Dendritic cells express MHC class II and B7 molecules that can recruit CD4 + T cells to help killer T cells. 3) (16 pts). In a few words, describe the main phenotype and main cause of the following mice: Mice: Main phenotype/problem (2 pts, e.g. die, arrest at DN T cell stage): Main cause (2 pts, be specific with the molecular mechanisms) TLR4-/- mice infected with Salmonella (Gram- bacteria) die, can't clear infection TLR4 recognizes LPS present in Gram- bacteria. Without it, mice are susceptible to Gram- bacteria infection Human patients with CD40L mutation recurrent infection or Hyper IgM syndrome B cells unable to switch to other isotypes due to lack of T cell help....
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mcb150-fa10-mt1-Astar Winoto-soln - Fall 2010 MCB 150...

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