Spring2010ExamIFormAAnswerKey - Exam I: Form A 153L SPRING...

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Exam I : Form A Name:_____________________ 153L SPRING 2010 TA:_________Section:______ Chem 153L, SPRING 2010 Exam I April 27, 2010 TA Use Only: Be sure to: Write your name on each page. Check that there are 6 pages including the cover page. Show all work – for math problems, if strategy is not shown , then points will not be awarded! Do not skip logical steps in explaining your reasoning. Keep answers direct. Do not repeat the question in your answer. Run-on sentences will be grammatically corrected & then graded based on the new sentence count. “Shotgun” answers (i.e. full of keywords in a nonsensical fashion) can receive zero credit. Multiple choice questions could have more than one right answer. Wrong answer(s) result(s) in deductions. Score: E1.______E2.______ E3_______ E4_______ E5________= _______ / 80pts.
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1. (+3) In the space provided below, list the three main steps that we will employ to prepare our crude extract and the basic purpose of each step. 1 st Step: __ Blending, lysis of cells to collect cellular extract. (+1) 2 nd Step: __ Centrifugation, removal of insoluble dense cellular debris. (+1) 3 rd Step: __ Filtration, removal of insoluble less dense cellular debris. (+1) 2. How will you use the volumes of each purification step during LDH LAB 1? (Circle all that apply) a) Qualitatively monitor the progress of your steps. b) Use total volumes of each step, which include the test aliquot, for the purification table. c) Determine the optimal dilution factor of 40% (NH 4 ) 2 SO 4 step enzyme assays. d) Use total volume of each step, which include the test aliquot, for (NH 4 ) 2 SO 4 steps. e) Determine the optimal dilution factor of the crude enzyme assays. Correct Answers: (+6, +2 for each) A – Understanding your steps and making reasonable estimations of volumes and mass allows you to evaluate the progress of your experiment of whether the actual volumes measure up to your predictions (and makes you more observant). B – You need the total volume including the test aliquot to determine the total amount of enzyme and protein. C – Since you should have already tested the crude volume, you would know the concentration of enzyme or the optimal dilution factor. In the subsequent steps, you should look at volumes of both the crude en enzyme assay since volumes are one of the two parameters that affect the change in concentration (the other is the amount recovered). Change in concentration requires proportional changes to the dilution factors used in the preceding step relative to the subsequent steps. This is true when looking at the volumes of the crude to 40% ammonium sulfate steps. Incorrect Answers: (- 2 pt for each, do not deduct beyond the worth of the question.) D – You need to look at the total volume minus the aliquot for ammonium sulfate steps. E – The crude’s optimal dilution factor is unknown because the enzyme concentration is
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This note was uploaded on 10/07/2010 for the course POLI SCI 40 taught by Professor Sch during the Spring '10 term at UCLA.

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Spring2010ExamIFormAAnswerKey - Exam I: Form A 153L SPRING...

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