Practice Exam

Practice Exam - BIS 102 Prof C Gasser 96 1 The figure below...

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BIS 102, Prof. C. Gasser 96 1. The figure below represents an isoelectric focusing (IEF) gel on which three protein samples (A, B, and C) were run to completion. The locations of the two electrodes are indicated by the “+” and "-" signs. a) (4) Which sample includes a protein with the highest pI? (circle one) A B C High pI is a basic protein that will initially have a “+” charge and will move toward the “-“ pole. The illustration below shows the result of sodium dodecyl sulfate (SDS, and also including ß-mercaptoethanol) polyacrylamide gel electrophoresis of the same samples that were examined on the IEF gel above. The gel was stained with commassie blue dye. The direction of migration was from top to bottom. A B C M b) (4) The size markers used on the gel are in the lane labeled “M” and are 10 kilodaltons (kD), 20 kD, 50 kD, and 90 kD in molecular weight. What is the approximate molecular weight of the protein visible in sample “B”? 50 kD, smaller proteins move more rapidly through the gel so the markers go from smallest to largest going from bottom to top of the gel. The band in B migrates with the 50 kD marker. + - A B C
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BIS 102, Prof. C. Gasser 97 2. In the space to the left of each of descriptions below, write the letters corresponding to all of the methods to which that statement applies. All correct answers must be given for full credit. (3 points each) A. Gel filtration. B. Isoelectric focusing gel electrophoresis. C. Ion exchange chromatography. D. Ligand affinity chromatography. E. Antibody columns. F. SDS polyacrylamide gel electrophoresis. G. Reverse phase chromatography. B, C can separate proteins on the basis of pI. A, C, D, E, G can be readily adapted for purification of large amounts of protein. D, E can commonly be used to purify a protein from a complex mixture in a single step. A, F separates proteins on the basis of size/molecular weight. G would likely work well to separate integral membrane proteins from soluble cytosolic proteins. D requires some knowledge of the activity of the protein for separation. F proteins are denatured when separated by this method. 3. (15) You have identified a new compound (call it "X") which, when added to a solution, significantly weakens salt bridges without affecting other types of weak chemical interactions. X is added to a tube of hemoglobin at pH7 at equilibrium with air and with a standard concentration of BPG. For each of the following, circle the letter to indicate if the addition of X will lead to an increase (I), decrease (D), or leave unchanged (U) the listed property of the hemoglobin solution (relative to the solution without added X). (3 points each). Numerous salt bridges stabilize the deoxy state. Weakening these salt bridges would favor the oxy state.
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This note was uploaded on 09/08/2010 for the course BIS BIS 102 taught by Professor Hilt during the Spring '09 term at UC Davis.

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Practice Exam - BIS 102 Prof C Gasser 96 1 The figure below...

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