CumFinal-2006Key - CUMULATIVE FINAL EXAM: VERSION 1 (MARK 1...

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CUMULATIVE FINAL EXAM: VERSION 1 (MARK 1 IN FIRST COLUMN OF “DAY” ANSWER ALL QUESTIONS ON THE OPSCAN SHEET WITH PENCIL 8 1. You are separating amino acids and peptides on a column of amine-modified polystyrene beads. Which one of these emerges from the column first? a. valine b. aspartic acid c. glutamine d. lysyl-lysine e. glycine 2. You have been given two proteins to characterize. One, “A,” is buried within a membrane and the other, “B,” is a completely soluble cytosolic protein. Which statement about the role of a leucine side chain in stabilizing the structures of the proteins is correct? a. In membrane protein A, the leucine side chain is likely to be found lining the interior of a proton channel, while in cytosolic protein B, the leucine side chain is likely to be tied up in an ion pair on the protein outer surface. b. In membrane protein A, the leucine side chain is likely to be found on the surface interacting via van der Waals forces with fatty acid side chains, while the side chain is buried within the interior of cytosolic protein B to avoid formation of clatherate structures in the solvent. c. In membrane protein A, the leucine side chain forms ordered structures with the fatty acid side chains which reduce the entropy of the system, whereas in cytosolic protein B, the leucine side chain orders the solvent to increase the entropy of the system. d. In membrane protein A, the leucine side chain is likely to participate in the catalytic mechanism, whereas in cytosolic protein B, the leucine side chain is likely to have no catalytic role. e. In membrane protein A, the leucine side chain binds to negatively charged phospholipids, whereas in cytosolic protein B, the leucine could interact with the guanidino group of arginine via London dispersion forces. 3. The pI (isoionic point) of the tetrapeptide gly-tyr-tyr-ala lies: a. between pH 2 and pH 5 b. at pH 5 c. between pH 2 and pH 9 d. at pH 10.5 e. above pH 11
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CUMULATIVE FINAL EXAM: VERSION 1 (MARK 1 IN FIRST COLUMN OF “DAY” ANSWER ALL QUESTIONS ON THE OPSCAN SHEET WITH PENCIL 9 4. You are using the technique of gel filtration chromatography on dextran beads to separate two proteins, cytochrome c (a 11,000 MW monomer) and pyruvate decarboxylase (a 250,000 MW tetramer). Which statement best describes your successful efforts. a. the two proteins are eluted from the column with a pH gradient starting at low pH and ending at high pH. Cytochrome c emerges first under these conditions. b. the two proteins are eluted from the column with a gradient of increasing NaCl concentration. Cytochrome c emerges first under these conditions. c. a gradient of increasing ionic strength will result in cytochrome c emerging first from the column, whereas a gradient of increasing hydophobicity will result in pyruvate decarboxylase emerging first from the column. d. an aqueous buffer of moderate ionic strength will be sufficient to elute both proteins
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This note was uploaded on 04/09/2008 for the course BIOCHEMIST 361 taught by Professor Haltiwanger during the Fall '08 term at SUNY Stony Brook.

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CumFinal-2006Key - CUMULATIVE FINAL EXAM: VERSION 1 (MARK 1...

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