2007exam2key - Second midterm - Biochemistry 442 KEY May...

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1 Second midterm - Biochemistry 442 KEY May 15, 2007 Name: _______________________ Student #:________________________ -5 points if your name is missing or not legible! Be specific in your answers! They do not need to be long, but be sure to clearly identify the important molecules when asked. 1) 21 points As a research scientist in a Department of Chemical Biology, you search libraries of chemicals for molecules that inhibit motors. You identify one chemical that inhibits all plus end-directed motors you call plusocine, and one that inhibits all minus end directed motors you call minusocine. Which chemical would you use if you wanted to inhibit the following events in a cell? Note that in some cases you might use both chemicals for maximum effect. Just name the chemical(s) you would use. A) The movement of the chromosome to the centrosome during Anaphase? Minusocine B) The movement of neurotransmitter-containing vesicles to the ends of axons? Plusocine C) Muscle contraction? Plusocine D) The breakdown of the nuclear envelope at prometaphase? Minusocine E) The movement of the chromosome towards one centrosome during prometaphase (when the kinetochore is first captured on one side)? Minusocine F) The movement of the centrosomes to the edges of the cell during anaphase? Minusocine and Plusocine G) The movement of LDL receptor containing vesicles from the cell surface to the endosome? Minusocine Each correct answer worth 3 points. -1.5 points if answered 'both' when only one correct answer, or if gave only plusocine or minusocine when correct answer was 'both'. 2) 14 points After studying for your 442 midterm, you decide that warts, which are caused by viral infection, should not get a nice suntan unlike the rest of your skin. Why is that? Provide a complete molecular explanation (i.e. be sure you explain how tanning works and how that relates to warts).
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2 When skin cells are exposed to the sun they turn on p53 gene expression, which produces pomc, which is cleaved to produce MSH, which turns on melanin synthesis in melanocytes. Warts contain papilloma virus (HPV). The E6 protein in HPV binds p53 and prevents it from functioning, so warts should not get tanned. Complete pathway: increase level of p53 2 points activate gene pomc 2 points make α -MSH 2 points stimulate melanin release 2 points Wart explanation: HPV infection 2 points virus protein E6 involved 2 points p53 sequestered by binding of E6 2 points 3) 15 points Working in a research lab you develop an antibody that specifically recognizes the human Snail protein. Thinking back to all the wonderful things you learned in 442,
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This note was uploaded on 04/07/2008 for the course BIO 355 taught by Professor Uchwitz,brianjoseph during the Spring '08 term at University of Washington.

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2007exam2key - Second midterm - Biochemistry 442 KEY May...

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