2008mcb2014fmay_2_jr

2008mcb2014fmay_2_jr - University of Cape Town Department...

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University of Cape Town Course Code: MCB2014F Course Name: Macromolecules Test 2 May 2008 (Total = 60 marks) (note that multiple choice questions will be subjected to negative marking) A. Carbohydrates and glycoconjugates (15 marks) 1. Shown below is a deoxy sugar viz. rhamnose which is a component of ouabain, a highly toxic cardiac glycoside found in the bark of the ouabaio tree. Please write down its full name, ie rhamnose and indicating whether it is an L or D sugar and whether it is the α or β anomer (eg a glucose molecule might be labeled α -D-glucose). (1) 2. Shown below is a Fischer projection of a monosaccharide that you were asked to know. (a) Please draw a Haworth representation of the above sugar as a furanose and in the α anomeric form (3) (b) Write down the name of this sugar indicating whether it is L or D. (1) 3. Glycogen is split into its monosaccharide elements by stepwise phosphorolytic cleavage of glucose units. Please complete the reaction (ie draw the products resulting from one step) indicated in the following diagram and answer some questions. (a) Complete one step of the following reaction: (3) (b) Is the end of the chain marked ‘A’ the reducing end or the nonreducing end? (1) (c) What is the full name of the specific enzyme (marked ‘B’ in the diagram) that carries out this reaction in the body? (1) 1 SECTION A (40 marks) Dr J Rodrigues
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The following questions (4 to 8) are of the multiple choice type (choose the most appropriate answer): 4. Referring to the structure of ATP as shown below, which of the following statements are true? A. contains a pyranose ring B. contains a β -N-glycosidic linkage C. exists in equilibrium with the open Fischer structure of the sugar D. contains a ketose sugar E. only B and D are correct (1) 5. Lactase deficiency is characterized by the inability to hydrolyze
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2008mcb2014fmay_2_jr - University of Cape Town Department...

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