exam-answers_2005f - MCB110 FINAL Dec 13, 2005 . Your name...

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MCB110 FINAL Dec 13, 2005 . Your name and student ID QUESTION POINTS 1 (25 points) 2 (10 points) 3 (15 points) 4 (10 points) 5 (20 points) 6 (20 points) 7 (15 points) 8 (20 points) 9 (25 points) 10 (40 points) 11 (30 points) 12 (20 points) 13 (14 points) 14 (21 points) 15 (9 points) 16 (6 points) TOTAL (300 points) WARNING: Your exam will be taken apart and each question graded separately. Therefore, if you do not put your name and ID# on every page or if you write an answer for one question on the backside of a page for a different question you are in danger of irreversibly LOSING POINTS!
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MCB 110 Page 2/11 Fall 2005 Final Name___________________________________ SID _______________________ Constants that you may need in the exam: R = 0.025 kcal/(mol . degree centigrade); N A = 6.02 10 23 mol -1 ; F = 23.06 kcal/mol.V 1. – Indicate true of false for the following statements (25 points, 5 each): (a) Lipids rafts are regions in biological membrane where the fluidity of lipids is reduced (b) Lipids rafts are enriched in sphingolipids (c) Lipids rafts are enriched in cholesterol (d) Lipids rafts are enriched in GPI-anchored proteins (e) Lipids rafts diffuse on the lipid bilayer All true 2. - Which are the two main protein folds for the transmembrane region of integral membrane proteins? (5 points) Which one of them can be predicted from hydropathy plots and why? (5 points) The two main transmembrane domain structures are all alpha helical, or beta barrels. In the first case the fold requires stretches of 20 or more hydrophobic residues that can be detected in hydropathy plots. In the second hydrophobic and hydrophilic residues alternate, a pattern that will not be detected by hydrophathy plots, in which the average hydrophobic character around a given residue is calculated. 3. – You are studying a protein that resides in the smooth ER and have created a GFP fusion to visualize it by fluorescence microscopy in living cells. What technique will you use to determine if the protein is able to diffuse in the membrane of the ER? (5 points) What results would you expect if the protein were fully mobile or unable to diffuse at all? (10 points). I would use FRAP (fluorescence recovery after photo-bleaching). If the protein were totally mobile I would expect close to total recovery of the bleach area. It totally unable to diffuse the bleached area will remain dark (no recovery). (And if a student chooses SPT as the technique, will you take that as a valid answer? NO, the whole point is that they created a GFP!)
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MCB 110 Page 3/11 Fall 2005 Final Name___________________________________ SID _______________________ 4. – The concentration of Cl - ions in and out of a cell is 10 and 100 mM, respectively (maintained by an ATPase pump). In which direction will Cl - ions move when Cl - channels open? Show how you came to that conclusion (15 points). The
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This note was uploaded on 03/08/2010 for the course MCB 110 taught by Professor Alber,zhou,nogales during the Fall '07 term at University of California, Berkeley.

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exam-answers_2005f - MCB110 FINAL Dec 13, 2005 . Your name...

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