BCHE3030.pdf - ~ J:Ii ~ ~'f:>c ~ Jf Y&Alt FiT:1f Page 1 of...

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~ - J( (# :Ii Jf) Page 1 of 5 Y.&Alt FiT :1f ~ 1Hll ~r ~ ~ 'f :>c. *- ~ Copyright Reserved The Chinese University of Hong Kong ~O-O~~O--~~T~M#@~~ Course Examination 2 nd Term, 2010-2011 if'!- § Mil tt.&.,t ~1t Course Code & Title : :sCHE3030 Methods in Bioc~emis'!!:y- ~M +* ~Hi Time allowed 2 bours o minutes ~1o..U&§! &§! Student LD. No. Seat No.: Instructions: 1. Put the answers for (i) PAPERS I and II in separate answer books. (ii) MULTIPLE CHOICE QUESTIONS on the question paper. 2. Return the question paper together with the answer books. PAPER I (40 marks) - Centrifugation and Radioisotopes SECTION A (10 marks): Answer ALL questions. Each question carries 5 marks. 1. A centrifuge is operated at a speed of2,000 xg. Calculate the revolutions per minute at a point equivalent to 5 cm from the axis of rotation. 2. An unused 500 microcurie vial of 125r (Half-life = 60 days) has decayed for 15 days. Calculate the radioactivity remained in the vial. SECTION B (30 marks): Answer TWO out of tlIree questions. Each question carries 15 marks. 1. Comment on the pros and cons of using differential oentrifugation and rate-zonal centrifugation to isolate subcellular organelles. . 2. Coinment on the pros and cons of using 3R, 35S and 32 p in protein sciences. 3. Researcher Thomas Parkinson is planning a density gradient centrifugation experiment to study protein-DNA interaction. He has obtained some purified protein HAP and 32P-Iabeled DNA fragment (200 bp long). He is provided with density media, CsCI, Ficol1, glycerol and sucrose. No anti-HAP antibody is available. Based on what you have learned in BCHE3030, suggest an experimental protocol.
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jf;.::. J{ (# Ji. A) Page 2 of5 Course Code *I- El ~Mt.: BCHE3030 ._----- PAPER II (60 marks) - Electrophoresis and, Mass Spectrometry SECTION C (10 marks): Multiple Choice Questions. Each question carries 1 mark. Answer ALL questions. Select the BEST answer for each question. Put the answers in the boxes provided. Multiple Choice Questions Not to be provided P.2 - P.3
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Course Code # EJ MiJtt: BCHE3030 ~ \!!l j{ (# li J{) Page 4 of5 SECTION D (20 marks): Answer ANY FOUR questions. Each question carries 5 marks. 1. The electrode buffer in SDS-PAGE is Tris-glycine, pH 8.3. Suppose you have prepared the solution and found that the pH was 8.8, is it preferable tQ bring the pH back to 8.3? . If yes, what should be done? 2. In two-dimensional electrophoresis of proteins, is it possible to run SDS-PAGE first, followed by IEF? Why? ' 3. What are the two most important characteristics of molecule that affect electrophoretic mobilities? Explain how they are involved in the electrophoretic analysis of nucleic acids. 4. Using ~SI as the ionization method, you obtained the m~s spectrum of a freshly prepared protein sample. After one month of storage, the same; protein sample was analyzed. The new mass spectrum showed peaks at the same rn/z values (lS the original one, but with a shift in the relative intensities ofthe peak towards species with lower rn/z values. Explain the observation.
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