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Midterm II - University of British Columbia Mid-term exam...

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Unformatted text preview: University of British Columbia Mid-term exam ll - August 5, 2008 Biochemistry 300 - Summer session Time: 1.5 hours Total Marks: 100 Candidate’s Name: (Please print family name first.) Student Number: Candidate’s Signature: This examination consists of 3 parts A, B, and C. Part B has 15 questions and part C has 8 questions. The exam has a total of 10 pages. Please check to ensure that this paper is complete. Answer all questions on this examination paper in the space provided. Read and observe the following rules: 1. Each candidate should be prepared to produce, upon request, hiS/her library/AMS card. 2. No candidate shall be permitted to enter the examination after the expiration of V2 hour, or to leave during the first 1/2 hour of the examination. . 3. Candidates are not permitted to ask questions of the invigilators, except in cases of supposed errors or ambiguities in examination questions. CAUTlON - Candidates guilty of any of the following, or similar, dishonest practices shall be immediately dismissed from the examination and shall be liable to disciplinary action: a) making use of any books, electronic storage devices, papers or memoranda, or cassette recorders other than those authorized by the- examiners; b) speaking or communicating with other candidates; c) purposely exposing written papers -to the view of other candidates. '_ d) The plea of accident or forgetfulness shall not be received. 4.' Smoking is not permitted during examinations. 5. Cellular telephones must be fully turned fl. Mark Obtained: I100 i, i l l . l l i l i . l l i i 2 t Equations & Constants: K=°C+273 AG'=AH—TAS F: 96,480 JN mol AG°’ = mFAEo' R: 8.315 J/mol K AG, = AG'° + RT In 191M [AHB] Vo = 'Vmax([S]/([S] + Km)) Where A & B are reactants and C & D are products PH = We + |09(lA‘]/[HA]) 1N0 = 1Nmax + (KmNmax)(1/[S]) Part A. Matching terms. Chose from the following list below and assign a number. Not all terms will be used. (20 marks) 1. Eicosanoids , 16. Waxes 2. Subunit a 17. Propionyl CoA 3. Malonyl 00A 18. Subunit 0 complex 4. lsopentenyl pyrophosphate 19. Lateral diffusion 5. Acetyl CoA ACP transacetylase 20. Acyl CoA transferase 6. Chylomicrons 21. Phosphatidyl ethanolamine . 7. Phosphatidyl choline 22. Very low density lipoproteins 8. Phosphatidyl serine 23. Testosterone 9. Transverse diffusion 24. a—1,6-glucosidase 10.8phingolipids 25. Famese pyrophosphate 11.Glycocholate 26. Cholesterol 12.Malonyl CoA ACP transferase 27. Liver glycogen phosphorylase 13.Active transport 28. Subunit A 14. Succinyl CoA 29. ‘ Geranyl pyrophosphate 15. Low density lipoproteins 30. Muscle glycogen phosphorylase A. In McArdle’s disease, this enzyme is either inactive or missing. B._ J “Prossss-taglandins the X creating pain” .l‘. Where X is: C. The only lipoprotein particle that contains ApoB48. D Phospholipids commonly exhibit this type of movement in membranes. E . - lt catalyzes the transfer of an acyl group from acyl ACP (Acyl Carrier Protein) ' to a thiol group on B-ketoacyl ACP synthase. F. In ATP synthase, it freely rotates. I G. Odd numbered fatty acids are directly broken down to Acetyl CoA and this molecule. ‘ o—eao—e—O‘ H ' 0' 0‘ J, HO Part B. Multiple Choice. Circle the best answer. (30 marks) 1.- NHE (Na+/H+ exchanger) proteins move sodium ions and protons as diagrammed below: ' Vesch-e Based on the diagram, NHEs can be classified as: Secondary active symporters. lon channels. Primary active antiporters. Secondary active antiporters. Primary active symporters. she-923.!» 2. All of the following are symptoms of McArdle’s disease EXCEPT: a. Inability to produce lactate upon strenuous exercise. . High concentrations of myoglobin in the blood. . High levels of serum creatine kinase. b c d. Hypoglycemia (low serum glucose). e. Fatigue and pain upon strenuous exercise. 3. Rotenone blocks electron transfer between iron-sulfur clusters in complex I. Which of the following is true of mitochondria treated with rotenone? Cytochrome a3 is primarily reduced. FMN is primarily reduced as FMNHZ. FAD is primarily reduced as FADHz. . There are high levels of ubiquinol in the inner mitochondrial membrane. new» 4 High levels of cholesterol In the liver result In the following EXCEPT: a. b. c. d. Decreased translation (protein synthesis) of HMG CoA reductase mRNA. Increased HMG- CoA reductase protein degradation. Release of Sterol Regulatory Element Binding Protein, which In turn decreases transcription (mRNA synthesis) of the HMG- CoA reductase gene. None of the above (i e. all are true!). 5. Bacterial membranes: finenvm A.re asymmetric. Contain cholesterol to decrease acyl chain mobility at high temperatures. Have a high Tm at a low temperature. Contain phospholipids with unsaturated fatty acids at high temperatures. a and b a, b, and c. 6 What Is the ATP yield if the structure below Is completely oxidized to C02 and H20? For simplicity’ s sake, assume it costs 1.5 ATP/double bond to convert an unsaturated fatty acid to a saturated fatty acid. 99.0.65» 0 MW H30 800.31 80. 78. 84. 94. 82. 7. Which one of the following statements about glycogen synthase is NOT correct? a. It is especially predominant in liver and muscle. b. The donor molecule is a sugar nucleotide. . c. it adds glucose units to the non- -reducing end of glycogen branches. d. e. b and d. It forms d(1->6) glycosidic bonds. ..8 Which statement Is true about cells treated with high concentrations of Oubain? a. b. c. d. They would contain high levels of sodium. They would contain high levels of potassium. The cytosol would be negatively charged relative to the extracellular matrix. Their Na /K ATPases would not be phosphorylated. 9. High density lipoprotein particles: '99?!» Contain a large amount of triacylglycerides. Are the largest of the lipoprotein particles. Contain lecithin- cholesterol acyltransferase Are synthesized by peripheral tissues such as muscle to carry cholesterol back to the liver 10.Which is the correct order of function of the following enzymes of [3 oxidation? 1. —h drox ac I—CoA deh droenase m 3. Eno l-CoAh dratase 4. Ac l-CoA deh droenase ’ a 123 b.341 c.4,3,1 d 143 11.Which of the following is NOT true about movement of free fatty acids into matrix of mitochondrion? Ia. Acyl CoA synthetase hydrolyzes ATP to ADP and Pi. . b. Carnitine acyl transferase ll is located in the mitochondrial matrix. c. Carnitine acyl transferase I primarily transfers acyl groups from acyl CoA to carnitine. d. Malonyl CoA inhibits carnitine acyl transferase l. 12.The ATP/ADP translocase: a. is ultimately driven by the proton gradient. b. Pumps ADP into thecytosol. c. is optional for oxidative phosphorylation. d. Results in the movement of a net charge of -1 into the matrix. 13.The following apply to the breakdown of glycogen to glucose EXCEPT: a. It usually involves an intramolecular shift of a functional group. b. Debranching involves the transfer of glucose residues from One chain to another. ~ c. it occurs at the non-reducing end of the glycogen chain. d. It involves hydrolysis of d(1 94) glycosidic bonds. e. None of the above (i.e. all are truel). ' 14. ingestion of large amounts of 2,4-dinitrophenol result in: a. An increased P20 (Phosphate:0xygen) ratio. b. A decreased P20 ratio. c. No change to the P:Q ratio. d. A large proton gradient. e. c and d. 15.An individual with a homozygous recessive mutation in Apolipoprotein B100 COULD have: a. A low HDL/LDL ratio. b. Increased LDL levels in the blood. . An increased risk of coronary heart disease. c d. Functional LDL receptors in the plasma membrane. e. All of the above. Part C: Short Answer Questions: 1. Given the following standard reduction potentials: 1/2 Reaction Eo’ (Volts) NAD+ + 2H+ + 26- ‘9 NADH + H+ t-0.320 ‘ FAD + 2H+ + 26' —) FADHz -0.219 Q + 2H+ + 26' '9 QH2 0.045 ZCyt C(ox) + 26- 9 20W: C(red) 0.250 ZCyt am + 28— 9 ZCYt a(red) 0.290 1/2 02 + 26' '9 ZHZO 0.816 Calculate the change in Gibb’s free energy that results from the transfer of two electrons from two molecules of Cyt. c to half a molecule of 02 under at standard conditions. (4 marks) » 2. Though work in your lab, you have created VLDL particles that are normal in every aspect EXCEPT their cholesterol ester (CE) content has been radioactively labeled. ' This allows you to detect the location of the CEs in the body. You inject these VLDL particles into mice and track the location of the radioactivity over time. Based on your knowledge of the course, predict the location and amount of radiation in each of the tissues in the chart below, To indicate amount, use the following: — None, + a little, ++ a moderate amount, +++ a lot/most. The first column has been completed as an example. No mice were harmed in this experiment! (4 marks) 3. In mammals, alcohol is primarily broken down in the liver mitochondrial matrix by the following pathway: ' . ATP AMP NAD+ NADH+H+ NAD” NADH+H+ CoASH PH 5 5 C? E / 9?. § / 9 CHscHon CH3cH CH3CO CH3cOSCoA Ethanol Acetaldehyde Acetate AcetleoA Alcohol Acetaldehyde Thiokinase Dehydrogenase Dehydrogenase [Acetyl CoA synthetase As a result of the above process, binge drinkers and chronic alcoholics have high concentrations of Acetyl CoA and an extremely high NADH/NAD+ ratio in the matrix and cytosol. 3a. What effect would consuming large amounts of alcohol have on the Krebs cycle? (4 marks) . 3b. What effect would consuming large amounts of alcohol have on oxidative phosphorylation (specifically the electron transport chain & ATP production)? Why? (4 marks) ~ 3c. What effect would consuming large amounts of alcohol have on the Cori cycle (specifically gluconeogenesis and lactate levels)? Be specific! (4 marks) 3d. What effect would consuming large amounts of alcohol have on fatty acid synthesis and B-oxidation? Be specific! (5 marks) 4. Draw the structure of sphingomyelin containing linoleate as the attached fatty acid. (4 marks) 5. One of the steps in fatty acid synthesis involves the reduction of a carbonyl group. What is the NEXT step in the process? Show structures and list any cofactors required for the reaction. Also, indicate the names of the structures and enzyme involved. (5 marks) 6. It may not be surprising to learn that mammalian cells have two isoZymes (enzymes that catalyze the same reaction but have different primary sequence) of malate dehydrogenase. One isozyme is located in the cytosol while the other is located in the mitochondrial matrix. Which metabolic processes (covered in class) would be affected by a mutation that inactivates CYTOSOLIC malate dehydrogenase in liver cells. Why? Be specific! (6 marks) 7. Glycogen storage disorder type l (von Gierke's disease) is an autosomal recessive genetic disorder where glucose—6-phosphatase is inactive or missing. If left untreated, it is lethal in early childhood. Which pathways are altered in von Gierke’s disease? Why is it lethal? (4 marks) 8. You are a graduate student studying the mechanism of ATP synthase and have recently made a temperature sensitive mutation (a mutation that functions normally (like ' wildtype) at permissive temperature but has an altered behavior (phenotype) at non- permissive temperatUres) in the gamma protein. When isolated mitochondria containing this mutation are shifted to the non-permissive temperature you observe the following: i. Oxygen consumption increases dramatically ii. ATP production decreases rapidly Based on your knowledge of the course, what effect does this mutation have on ATP synthase? Explain your answer! (Hint: There are at least two possible answers!) ' (6 marks) - ' 10 1: l l l i t z i ...
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