BIS102_02WhiteKey

BIS102_02WhiteKey - Name White Key Last, First BIS102-02,...

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Name White Key BIS102-02, Spring ‘09, Page 1 of 7 Last, First C. S. Gasser BioSci 102-02 Second Midterm, May 19, 2009 Instructions: There are sevn pages in this exam including the cover sheet, please count them before you start to make sure all are present. Write your name on each page of the exam. Write your answers in the space provided below each question. If you need more space use the back of the page and indicate clearly that you have continued your answer on the back. Do not use additional paper. For calculation problems a clear line of calculations leading to your final answer must be shown to obtain full credit. Use the following pK a values for the exam. Amino Acid α -NH 2 α -COOH R-group log 1.0 = 0.00 Ala, Gly, Ile, Leu, Val 9.7 2.3 log 1.5 = 0.18 Asn, Gln 9.0 2.1 log 2.0 = 0.30 Met, Ser, Trp 9.3 2.3 log 2.5 = 0.40 Phe 9.1 1.8 log 3.0 = 0.48 Pro 10.6 2.0 log 3.5 = 0.54 Thr 10.4 2.6 log 4.0 = 0.60 Asp 9.8 2.1 3.9 log 4.5 = 0.65 Glu 9.7 2.2 4.2 log 5.0 = 0.70 His 9.2 1.8 6.0 log 5.5 = 0.74 Cys 10.8 1.8 8.3 log 6.0 = 0.78 Tyr, Lys 9.1 2.2 10.0 log 6.5 = 0.81 Arg 9.0 2.2 12.5 log 7.0 = 0.85 log 7.5 = 0.88 Question Value Score log 8.0 = 0.90 1 15 log 8.5 = 0.93 2 15 log 9.0 = 0.95 3 15 log 9.5 = 0.98 4 18 log 10.0 = 1.00 5 18 6 6 R = 8.3 X 10 -3 kJ/°mol 7 12 25°C = 298K 8 10 9 26 10 15 Total 150
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Name White Key BIS102-02, Spring ‘09, Page 2 of 7 Last, First C. S. Gasser 1. (15) The diagram below shows a cross section of small region of a plasma membrane surrounding a red blood cell. This region of membrane includes a protein with a membrane- spanning alpha helix. Only the peptide backbone of the protein is illustrated. The letters "a" through "e" in the figure indicate specific molecules or regions of the protein (indicated by shading). In the blanks below fill in the letter of the structure which is most likely to correspond to the description provided. (only ONE letter per blank!). d - sphingolipid a glycosphingolipid c - peptide sequence - MLFVI hydrophobic and no helix breakers so membrane spanning helix by process of elimination b - peptide sequence – YLPGI hydrophobic so on interior, but helix breakers mean not in transmembrane region e - phospholipid a - peptide sequence - SQAND all hydrophilic so must be on outside of protein 2. An enzyme, E, catalyzes the reaction A < –> B leading to a 10 9 -fold increase in the reaction rate. Relative to a similar reaction in the absence of the enzyme, what effect does the enzyme have on each of the following? Circle "U" for unchanged, "I" for increased, "D" for decreased, or "N" for need more information to answer. Assume that compound B is in excess (relative to equilibrium) at the start of the reaction (3 pts. each).
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This note was uploaded on 01/29/2010 for the course BIS 102 taught by Professor Hilt during the Winter '08 term at UC Davis.

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BIS102_02WhiteKey - Name White Key Last, First BIS102-02,...

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