KERALA UNIVERSITY Ph.D. ENTRANCE EXAMINATION – 2013
FACULTY OF SCIENCES
Time: 140 Minutes Maximum Marks: 160
Note: Answer any twelve questions from Section B and one question from Section C in the subject concerned. In Section B, each question carries 10 marks. Section C carries 40 marks. In Section B an answer should not exceed 100 words. In Section C, an answer should not exceed 500 words.
SECTION – B
(1). Explain the term Chromatography. How are proteins separated by :
a. Affinity Chromatography
b. Ion-exchange chromatography.
(2). Given a mixture of proteins which contains a recombinant insulin among other proteins which of the above two chromatographic technique will you employ for purification of the insulin molecule. Why?
(3). Explain Beer Lamberts’s law. Describe an experiment to verify this law. Given that the Molar extinction coefficient of a compound in water is 25,000 at 550 nm and a solution of this compound in water gave an absorbance of 0.552 at 550 nm calculate the concentration of the compound.
(4). Explain the importance of-SH functional groups in stabilizing structure of proteins.
(5). Explain the principle of density gradient centrifugation and describe how this technique can be used in purification of cell organelles.