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Biochemistry 153CSpring 2005Second Examination_____________________ ___________________Last Name (Print) First Name (Print)1. Gluconeogenesis and the Pentose phosphate pathway (20)(12) A. Briefly define Gluconeogenesis B. describe the physiological conditions that favor Gluconeogenesis.C. What is the major organ that carries out gluconeogenesis? D. what two tissues are most dependent ongluconeogenesis under the physiological conditions that favor this process. E. Name the key allosteric ef-fector that reciprocally regulates both gluconeogenesis and glycolysis. F. Which of these two processes isfavored by high concentrations of this allosteric effector.(8) A. What are the two major functions of the pentose phosphate pathway? B. The overall rate of the firststage of the pentose phosphate pathway is determined by the activity of a critical enzyme, glucose-6-phosphate dehydrogenase. Assuming a constant supply of glucose-6-phosphate, what are the two most im-portant mechanisms for regulating the rate glucose-6-phosphate dehydrogenation? Question 1 2 3 4 5 TOTALPoints 20 20 20 20 20 100Score2. Lipids: Digestion & absorption; transport, deposition and mobilization (20)(8) For efficient digestion of triglycerides (TG) in the duodenum (upper part of small intestine) and the sub-sequent absorption of the digestion products (chiefly ß-monoglyceride and fatty acids) by intestinal ep-ithelial cells, the secretion of and intestinal hormone, Cholecystokinin, is essential. The 4 major effects ofthis hormone include [1] inhibition of the rate of gastric (stomach) emptying into the duodenum, [2] stim-ulation of the secretion of pancreatic lipase into the of the duodenum, [3] stimulation of the secretion ofbicarbonate into the duodenum and [4] stimulation of gallbladder contraction with the resultant release ofbile salts into the duodenum. Briefly explain how the function of each of these 4 processes or productscontributes to the efficiency of digestion of TG and absorption of the digestion products.(5) What is the major function of each of the following serum lipoproteins? [1] Chylomicrons, [2]VLDL,[3] LDL, [4] HDL, (give 2 major functions) Provide one sentence (or less) answers(7) Each of the following processes involved in lipid deposition or mobilization is stimulated, directly or indi-rectly, by either insulin or glucagon; provide the correct answers in the spaces provided: activation of adenylate cyclase [ ] activation of phosphodiesterase [ ]activation of acyl-CoA synthase [ ] secretion of VLDL from liver [ ]secretion of lipoprotein lipase [ ] activation of protein kinase [ ]activation of homone-sensitive lipase [ ]Biochemistry 153C, Exam 2Spring 2005 Page 23. Fatty acid oxidation, ketone bodies and cytochrome P450 oxygenations. (20)Only two of the five phrases correctly complete each statement. Select those two by circling the correspondingletters (A-E). If more than 2 letters are circled, no points will be given; 4 points (full credit) will be awarded fortwo correct answers, 2 points (half credit) will be awarded for one correct answer.One cycle of ß-oxidation of palmitoyl-CoA (a 16 carbon saturated fatty acid thioester)A requires 4 different enzymesB includes both a hydration step and 2 dehydrogenation steps.C yields less ATP than does the ß-oxidation of stearoyl-CoA (an 18 carbon fatty acid thioester)D yields more ATP than does the ß-oxidation of stearoyl-CoA (an 18 carbon fatty acid thioester)E includes both a dehydration step and a dehydrogenation step.In the ß-oxidation of a fatty acyl-CoA containing 17 carbon atomsA the final cycle would produce one molecule of acetyl-CoA and one of formyl-CoAB the final cycle would produce 2 molecules of acetyl-CoA.C the final cycle would produce one molecule of acetyl-CoA and one molecule of propionyl-CoA D eight cycles are required.E seven cycles are required. .The cytochrome P450 enzymes of the endoplasmic reticulum (ER) in the liverA are generally highly substrate inducible B carry out the ß-oxidation, in special organelles, of very long-chain fatty acids (C22 or greater). C can catalyze O2-dependent desaturation of long-chain saturated fatty acids to polyunsaturated derivatives.D are biosynthetic enzymes that synthesize many membrane lipids in higher animals.E initiate the oxidation of many aromatic hydrocarbons that may enter the body.The cytochrome P450 enzymes of the endoplasmic reticulum (ER) in the liverA are very potent carcinogens in most higher animals. B are involved in the overall regulation of membrane fluidity in response to metabolic needs. C require interaction with a reductase enzyme to become catalytically active.D require interaction with O2and a reduced pyridine nucleotide to carry out substrate oxygenation.E interacts with benzo(a)pyrene to convert this aromatic hydrocarbon into a potent anti-cancer agent. Ketone bodies formed in the liver (acetoacetic acid and ß-hydroxybutyric acid) A may enter the blood and pass through the blood-brain barrier to substitute for glucose as an energy source. B must first be converted to the CoA derivatives before they can cross the blood-brain barrier.C must first be converted to the CoA derivatives before they can exit the liverD are significantly produced when glycogen supplies are exhausted (i.e. prolonged fasting or starvation)E are formed by the action of P450 enzymes of long-chain fatty acids.Biochemistry 153C, Exam 2Spring 2005 Page 34. Fatty acid biosynthesis and its regulation; unsaturated fatty acids; prostaglandinsOnly two of the five phrases correctly complete each statement. Select those two by circling the correspondingletters (A-E). If more than 2 letters are circled, no points will be given; 4 points (full credit) will be awarded fortwo correct answers, 2 points (half credit) will be awarded for one correct answer.Acetyl-CoA carboxylaseA is an integral part of of the Type 1 fatty acid synthetase found in man and higher animals.B catalyzes the first committed step in the pathway for fatty acid biosynthesis.C is located in the endoplasmic reticulum (ER)D catalyzes the most rate-limiting step in the pathway for fatty acid biosynthesis.E is a polymeric enzyme that contains all of the activities necessary for fatty acid biosynthesis.In the regulation


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UCLA CHEM 153C - Second Examination

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