Old_Exam_3__2005 Spring_

Old_Exam_3__2005 Spring_ - FX/W 3) 3mg [0-53 Dru"...

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Unformatted text preview: FX/W 3) 3mg [0-53 Dru" Aiken emf {if/1.5100 Which one of the following enzymes is paired with an effector that results in a decrease in the enzyme’s activity? A) B) C) D) E) Enzyme Effector acetyl CoA carboxylase insulin hormone sensitive lipase glucagon carnitine acyl transferase-I malonyl CoA fatty acid synthase insulin lipoprotein lipase insulin Each of the following enzymes is involved in the same metabolic pathway, EXCEPT: A) acyl CoA dehydrogenase B) B-ketoacyl ACP reductase C) B-ketothiolase (thiolase) D) enoyl CoA hydratase E) B-hydroxyacyl CoA dehydrogenase Which one of the following statements about the triacylglycerols stored in adipose tissue is TRUE? A) They are hydrolyzed to form fatty acids and glycerol in response to high blood glucose. I B) They are hydrolyzed by a lipase that is activated by dephosphorylation. C) They are hydrolyzed by a lipase which is activated by a CAMP dependent protein kinaSe. D) Their hydrolysis leads directly to ketone body fonnation. E) They are synthesized in response to high blood glucagon. Which one of the following is involved in the ATP dependent activation of fatty acids for transport into the mitochondrion? A) B) C) D) E) fatty acyl CoA synthetase hormone sensitive lipase carnitine acyltransferase~l fatty acyl transferase citrate lyase Acetyl CoA has each of the following features, EXCEPT: A) B) C) D) E) It is a substrate for B-hydroxy B-methyl glutaryl CoA synthase. It is a product of citrate lyase. It is a substrate for malic enzyme. It is a product of ketone degradation. It is a product of B—ketothiolase 10. Which one of the following statements about ketone bodies is FALSE? A) They are normal fuels for heart muscle. B) They are synthesized in the liver from the metabolism of fatty acids. C) They include both acetone and acetoacetate. D) They require three acetyl COA molecules for their synthesis. E) Their blood concentration would be high in an individual who has high blood glucose concentrations. Which one of the following is NOT synthesized from cholesterol? A) cortisol B) testosterone C) estrogen D) mevalonate E) bile acids Which one of the following statements is FALSE? A) The presence of lipoprotein lipase on the surface of adipocytes is increased by the action of insulin. B) Very low density lipoprotein (VLDL) and high density lipoprotein (HDL) are similar in chemical composition. C) Peripheral tissues can be depleted of cholesterol by the passage of their cholesterol to HDL. D) ovastatin is a drug which lowers cholesterol levels by inhibiting B-hydroxy B-methylglutaryl CoA reductase. E) LDL and IDL are lipoproteins derived from the action of lipoprotein lipase on VLDL. Which one of the following statements is TRUE? A) Glucagon action leads to inactivation of hormone sensitive lipase. B) Insulin promotes the phosphorylation of acetyl CoA carboxylase. C) Glucagon action on adipocytes leads to increased CAMP concentration. D) Insulin action leads to the phosphorylation of hormone sensitive lipase. E) Phosphorylation of acetyl CoA carboxylase results in its activation. Which one of the following statements concerning fatty acid metabolism is FALSE? A) Each round of fatty acid biosynthesis requires the use of eight moles of malonyl CoA. B) FAD is a required cofactor in the conversion of fatty acyl COA to trans-AZ-enoyl CoA. C) Fatty acid catabolism to C02 produces a higher yield of ATP per carbon oxidized than carbohydrate or protein catabolism. D) Acetyl CoA carboxylase is activated by cinate. E) NAD+ is a required cofactor in the conversion of 3—hydroxy acyl CoA to 3-ketoacyl CoA. ll. 12. l3. 14. 15. Each of the following is an intermediate or required in phosphatidyl choline synthesis from glycerol, fatty acids and choline, EXCEPT: A) B) C) D) E) phosphorylcholine NADPH diacylglycerol phosphatidic acid CTP 3—hydroxybutyrate is A) B) C) D) E) synthesized from acetoacetate by an NADH—dependent dehydrogenase readily converted to glucose during a prolonged fast. produced in extrahepatic tissues and consumed by the liver a principle product of fatty acid synthesis a direct product from the breakdown of B-ketoacyl CoA. Which one of the following statements is TRUE concerning fatty acid biosynthesis and/or B—oxidation of fatty acids? A) B) C) D) E) Both are located in the cytosol Both use thiol esters as carriers of the fatty acyl group. Both release C02 during the metabolic pathway. Fatty acid biosynthesis uses only NADH as a reductant in the metabolic pathway. Fatty acid oxidation uses only NAD+ as an oxidant in the metabolic pathway. The end-product of the enzymes involved in fatty acid synthesis is A) fatty acyl CoA B) fatty acid C) fatty acyl ACP D) acetyl CoA E) malonyl CoA Which of the following pairs of enzymes does NOT require a nucleotide triphosphate as a substrate? A) Citrate lyase (citrate cleavage enzyme), glycerol kinase B) acetyl CoA carboxylase, protein kinase A C) cytidylyl transferase, propionyl CoA carboxylase D) camitine acyl transferase I, fatty acid synthase E) glycerol kinase, pyruvate carboxylase 16. 17. 18. 19. Which one of the following statements about membranes is TRUE? A) The phosphate and choline moieties (groups) of phosphatidyl choline are found at the center of the bimolecular leaflet of cellular membranes. B) molecules of phosphatidyl choline are arranged symmetrically across the plasma membrane bilayer (That is, their head groups are oriented equally toward the inside and outside of the cell). C) phospholipids flip—flop rapidly across the bimolecular leaflet of the membrane to achieve their final distribution. D) lateral diffusion of lipids and proteins in the bimolecular leaflet of membranes is fast. E) all biological membranes contain cholesterol. Which one of the following statements is FALSE concerning sterol/steroid metabolism? A) mixed function oxidases (P540 enzymes) which use NADPH and 02 are necessary for steroid hydroxylations. B) the formation of cholesterol from acetyl CoA is an anabolic process. C) the cholesterol in LDL is the ligand to which LDL receptors bind during receptor mediated cholesterol uptake by peripheral cells. D) the synthesis of LDL receptors is inhibited by high cellular cholesterol. E) isopentenyl pyrophosphate (active isoprene) is a metabolic precursor to both cholesterol and the bile acids. Each round of B—oxidation yields electrons which are passed to cofactors. Knowing which cofactors are involved, how many ATPs would you expect to be produced as a result of the reoxidation of the reduced cofactors produced after just one round of B—oxidation? Do not consider any oxidation of acetyl CoA. A) 2 B) 3 C) 4 D) 5 E) 6 Statins inhibit the activity of the enzyme B-hydroxy B—methylglutaryl CoA reductase because their structures are similar to the reductase product, mevalonate. Therefore, statins effectively inhibit cholesterol biosynthesis. On the basis of your knowledge of sterol biosynthesis and its regulation, which one of the following is most likely to occur as a result of statin administration? A) a decrease in synthesis of the enzyme B-hydroxy B—methylglutaryl CoA reductase. B) an increase in LDL receptors on the cell surface. C) increased uptake of cholesterol from peripheral cells by HDL. D) an increase in cholic acid synthesis. E) a decrease in cholesterol packaged into chylomicrons afier a meal. 20. 21. 22. 23. 24. Which one of the following statements is TRUE? A) Biotin is required for the carboxylation of propionyl CoA and acetyl CoA. B) Acyl carrier protein carries fatty acyl groups from the mitochondria to the cytosol. C) Biotin carries fatty acyl groups during fatty acid biosynthesis. D) Acyl carrier protein carries fatty acyl groups during fatty acid oxidation. E) Carnitine carries fatty acyl groups from the mitochondrion to the cytosol Which one of the following enzymes controls the rate—determining step in fatty acid synthesis? A) cytidylyl transferase B) fatty acyl transferase C) B-hydroxy-B-methyl glutaryl CoA synthase .D) acetyl CoA carboxylase E) fatty acyl CoA synthetase Triglycerides and phospholipids may have common precursors in each of the following EXCEPT: A) glycerol phosphate B) CDP choline C) phosphatidic acid D) fatty acyl CoA E) diacylglycerol In the course of fatty acid synthesis fiorn acetyl—CoA, intermediate chain length saturated fatty acyl groups are made. Which of the following represents the energy requirements for the synthesis of a saturated 12 carbon fatty acyl intermediate during this synthesis? A) B) C) D) E) 5 ATP + 5 NADPH 5 ATP + 10 NADPH 5 ATP + 12 NADPH 6 ATP + 10 NADPH 6 ATP + 12 NADPH Which one of the following is not an important component of the pathway for fatty acid biosynthesis and it regulation? A) B) C) D) E) concentration of citrate blood levels of glucagon concentration of fatty acyl CoAs carm'tine acyl transferase—II citrate lyase (cleavage enzyme) 25. 26. 27. 28. 29. Which one of the following reactions is responsible for the production of cytosolic NADPH to be used in fatty acid biosynthesis? A) B) C) D) E) Which of the following pairs of amino acids contains two nutritionally non—essential pyruvate + NADP+ ----- --> acetyl CoA + NADPH + CO; malate + NADP+ ------- --> oxaloacetate + NADPI-I lactate + NADP+ ------- —-> pymvate + NADPH malate + NADP+ ------- --> pyruvate + NADPH + CO; glycerol-3 phosphate + NADP+ ---- --> dihydroxyacetone phosphate + NADPH amino acids? A) B) C) D) E) Which of the following amino acids is not synthesized in mammals but can be supplied leucine and lysine proline and asparagine valine and serine phenylalanine and threonine glutamine and isoleucine by a dipeptide found in muscles? A) B) C) D) E) arginine phenylalanine histidine valine threonine Glutamate dehydrogenase is a key anaplerotic reaction that is activated by A) B) C) D) E) An aldimine is in equilibrium with ascorbate N-acetylglutamate ATP carnitine NAD+ by aminotransferases A) B) C) D) E) aldoxamine Witti g amine semialdehyde ketimine none of the above in reactions catalyzed 30. 31. 32. 33. 34. 35. Glutamate y—semialdehyde can be synthesized in a single enzyme—catalyzed reaction from A) B) C) D) E) Which of the following is the nearest precursor in the biosynthesis of proline? glutamine lysine ornithine succinate semialdehyde citrulline A) glutamate B) 3-phosphoglycerate C) oxaloacetate D) succinate E) pyruvate Tetrahydrofolate, the coenzyme derived from the vitamin folic acid, is required in the biosynthesis of: A) phenylalanine B) asparagine C) tyrosine D) arginine E) glycine Which of the following is required for the formation of 4-hydroxyproline? A) B) C) D) E) Non—classical phenylketonuria (also called malignant phenylketonuria) is a result of tetrahydro folate S-adenosylmethionine camosine tetrahydrobiopterin vitamin C (ascorbate) depressed formation of A) B) C) D) E) phenylalanine phenylketones such as phenylpyruvate tetrahydrobiopterin glutamate y-semialdehyde methylmalonate The major role of S-adenosylmethionine is to serve as A) B) C) D) E) a methionine donor. a substrate for specific kinases. an adenosine source for DNA and RNA biosynthesis. a methyl donor. a precursor in the biosynthesis of methionine containing hormones. 36. 37. 38. 39. 40. In the urea cycle, which of the following is the correct order of intermediates, starting with ammonia? (Note that not all of the intermediates are provided; nevertheless, one answer does list the intermediates in the order of their appearance in the urea cycle.) A) NH3, ornithine, arginiosuccinate, citrulline B) NH3, citrulline, arginosuccinate, arginine C) NH3, ornithine, arginine, citrulline D) NH3, citrulline, arginine, argininosuccinate E) NH3, arginine, citrulline, ornithine, camosine In argininosuccinate, shown below, the carbon labelled with an asterisk comes from: a6 “if” a *ooc—CHZ—CH—M%-C—vW~@¢§)3~C// ~— COO l I A) C02 " B) fumarate COO W5]ij C) ornithine D) citrulline E) aspartate Furnarate is produced in the urea cycle by the same enzyme that produces: A) AMP B) arginine C) ornithinc D) phosphate E) pyrophosphate Which of the following enzymes is required in a pathway to convert furnarate to aspartate? A) citrate synthase B) succinyl—CoA synthetase C) fiimaryl-COA synthetase D) fiimaryl-aspartate lyase E) aspartate aminotransferase Nitric oxide is an important vasodilator that modulates relaxation and artery wall diameters. It is produced from arginine by nitric oxide synthase, an enzyme that also produces: A) camosine B) omithine C) urea D) citrulline E) aspartate 41. Which of the following activates the enzyme that produces N-acetylglutamate from acetyl-CoA and glutamate? A) aspartate B) arginine C) malonyl-CoA D) methylmalonyl—COA E) carbamoyl phosphate 42. Which of the following is a solely ketogenic amino acid? A) tyrosine B) isoleucine C) try‘ptophan D) histidine E) lysine 43. As discussed in class, the degradation of histidine produces: (give best answer) A) oxaloacetate B) acetoacetate C) a-ketoglutarate D) succinyl-CoA E) pyruvate 44. Which of the following amino acids produces ubiquinone (coenzyme Q)? A) tryptophan B) asparagine C) histidine D) tyrosine E) valine 45. Alcaptonuria is an inborn error in metabolism associated with the degradation of: A) isoleucine B) histidine C) tyrosine D) tryptophan E) propionyl-COA 46. Elevated levels of methylmalonate in the blood plasma or urine are often associated with a deficiency of: A) any essential amino acid B) biotin C) homogentisate D) vitamin B12 E) valine 47. 48. 49. 50. Maple—syrup-urine disease is associated with a deficiency in an enzyme in the degradation of: A) B) C) D) E) Which of the following biomolecules will increase blood pressure? A) B) C) D) E) The rate-determining step in the biosynthesis of leukotrienes is: leucine methionine tryptophan tyrosine histidine thyroxin neurophysin vasopressin somatotropin prostaglandin 12 A) the formation of prostaglandin H B) the reaction with glutathione C) the release of arachidonate fiom the membranes D) the first step in the degradation of prostaglandins E) the step regulated by thyrotropin-releasing hormone Aspirin inhibits A) cyclooxygenase B) thromboxane synthase C) leukotriene A4 synthase D) phospholipase A; E) methylmalonyl—COA mutase ...
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This note was uploaded on 12/09/2011 for the course BCH 4024 taught by Professor Allison during the Spring '08 term at University of Florida.

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Old_Exam_3__2005 Spring_ - FX/W 3) 3mg [0-53 Dru"...

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