2009_Practice_Exam_I

2009_Practice_Exam_I - 1 BMB 402H Spring 2009 Practice Exam...

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BMB 402H Spring 2009 Practice Exam I NAME: _________________________________________________________ There are 17 questions on this exam worth a total of 100 points. Write your answer to each question in the space provided. If more space is needed, you may continue on the reverse side of the page; be sure to clearly indicate the question number. Write legibly to make grading easier. 1. Pathways involved in energy metabolism “talk” to one another to ensure that they are coordinately regulated. Based on your understanding of regulation of glycolysis and the TCA cycle, provide one example for the “cross-talk” between glycolysis and the TCA cycle. In your answer, you must explain how glycolysis “senses” the slowdown, or speeding up, of the TCA cycle and how it “responds” by slowing down, or speeding up, its activity. It is also important that you show the enzyme(s) in glycolysis that is (are) regulated in the example you have given. (6 points) 1
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2(a). List all the metabolic pathways that you have learned in the chapters covered on this exam, and name the ones whose activity is directly regulated by glucagon (as opposed to indirectly affected when a glucagon-regulated pathway is slowing down or speeding up). (4 points) 2(b). For the metabolic pathways whose activity is affected by glucagon, choose any one and explain why this regulation makes physiological sense. (3 points) 3. Some glycolytic intermediates are used as precursors by other metabolic pathways. For each of the following glycolytic intermediates, describe one metabolic reaction (outside glycolysis) that uses it as substrate. Use chemical structures, names, or abbreviations to show all the substrate(s), product(s), and any co-enzyme(s). Also name the enzyme involved. (6 points) (a). Fructose-6-phosphate (b). 1,3-bisphosphoglycerate 2
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4. A solution of glucose, labeled with radioisotope C 14 at the anomeric carbon, is added to an aerobic bacterial culture that is active in oxidizing glucose to generate energy. Draw the structure of citrate and indicate on the structure all the carbon(s) that will be initially labeled with C 14 . You must explain how you have arrived at your answer. Assume that pyruvate carboxylase is active under this metabolic condition. (8 points) 3
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5. Under anaerobic conditions, yeast cells can use glucose to synthesize malate in the presence of
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2009_Practice_Exam_I - 1 BMB 402H Spring 2009 Practice Exam...

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