2005mcb201sdeferred

2005mcb201sdeferred - University of Cape Town Department of...

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University of Cape Town Course Code: MCB201S Deferred Physiological Biochemistry Paper: 1 Date: 25 Jan 2006 – p.m. No.of pages: 10 Marks: 136 Time: 3 Hours Venue: Zoo 2 1 x Data sheet attached ANSWER ALL THE QUESTIONS In the interest of economy please write on both sides of the exam script Please answer each section in a different answer book. Section 1: Dr Jerry Rodrigues 91 Marks Carbohydrates: (18 marks) 1. Given are the Fischer projections of 8 sugars. You were told to know 5 of these 8 (A to E). Match the following names to the correct structures (a to h). Note that some hydrogens have been omitted for clarity. (A) D-fructose (B) D ribose (C) D-mannose (D) D-glucose (E) D-galactose (5) 1
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2. Indicate whether each of the following pairs of sugars are anomers, epimers or an aldose-ketose pair. a) D-glyceraldehyde and dihydroxyacetone b) D-glucose and D-mannose c) D-glucose and D-fructose d) α -D-glucose and β -D-glucose e) D-ribose and D-ribulose (5) 3. α -D-Mannose is a sweet-tasting sugar. β -D-Mannose, on the other hand, tastes bitter. A pure solution of α -D-mannose loses its sweet taste with time as it is converted into the β -anomer. a) Draw the β -anomer (1) b) Explain how it is formed from the α -anomer. (3) 4. If a polysaccharide is treated with methyl iodide, then subjected to acid hydrolysis, all the OH groups in the sugar will be methylated except for the anomeric OH and those OH groups involved in glycosidic linkages. When this procedure was carried out on a sample of the disaccharide trehalose, which is composed only of glucose, the only product obtained was determined to be 2’,3’,4’,6’-tetra-O-methyl-D-glucose. Propose a structure(s) for trehalose. (4) Immunology: (13 marks) 1. Define the following terms as applied to antibodies: (a) Segmental flexibility (2) (b) Myeloma proteins (2) 2. Mammalian antibodies are coded for by three unlinked gene clusters. a) What are these (3) b) How is an antibody assembled from the products of these clusters? (1) 2
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3. Specific enzyme proteins called RAG-1 and RAG-2 involved in DNA recombination were mutated or missing in the case of David, a boy born with SCID (severe combined immunodeficiency). The so-called ‘bubble boy’ died of an infection at the age of 12 years. Briefly describe what the problem was with his immune system. (3) 4. Which of the following is not a characteristic of plasma cells? a. They arise from B cells. b.
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This note was uploaded on 01/05/2011 for the course BLY 440 taught by Professor Williams during the Fall '10 term at Alabama.

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2005mcb201sdeferred - University of Cape Town Department of...

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