lastyearfinal07 - Last Name First Name Student Section...

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Last Name: ___________________ First Name: _______________ Student #: ____________ Section Number: ___________ Biology 200 Final Exam - Dec. 12, 2007 1. (6 marks). Cells at the Anaphase A and Anaphase B stages of mitosis are treated with taxol and colchicine. Indicate for each type of drug what the effects of these drugs would be on both Anaphase A and Anaphase B and why. 3 marks each: effect and explanation Taxol: prevents disassembly of MTs Colchicine: prevents assembly of MTs Effect on Taxol Colchicine Anaphase A Chromosomes would not move or move along MTs. Kinetochore MT disassembly at the kinetochore does not occur. (2 marks) None (1 mark) Anaphase B None (1mark) Interpolar MTs would not elongate; new tubulin units would not assemble on the (+) ends of the overlapping interpolar MTs. (2 marks) 2. (5 marks). Which of the following changes in cell membranes are likely to be seen when a cell culture growing at 37 o C is transferred to 25 o C? Indicate Yes or No, and briefly explain each case. No marks will be given for just stating Yes or No. a) Initial decrease in membrane fluidity b) Gradual replacement of shorter fatty acids by longer fatty acids in membrane phospholipids c) Gradual replacement of stearate (18 carbons, saturated) by oleate (18 carbons, 1 double bond) in the membrane phospholipids d) Enhanced rate of synthesis of unsaturated fatty acids e) Loss of integral proteins from the membrane 1 mark each: a) Yes; membrane fluidity is temperature dependent and shift to lower growth temperature will decrease membrane fluidity. b) No; longer chain fatty acids decrease membrane fluidity. c) Yes; unsaturated fatty acids increase membrane fluidity. d) Yes; unsaturated fatty acids increase membrane fluidity.
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