CH369 exam3f99 - a???“ 1. (1? pts) On the outline of...

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Unformatted text preview: a???“ 1. (1? pts) On the outline of electron transport below fill in the missing portions: a) at the entry points into electron transport indicate oxidation state and/or molecule b) fill in the missing components 0) circle the mobile electron carriers (1) indicate where each of the protein complexes function e) indicate which steps generate sufficient energy to support ATP synthesis 0.5 pt each reduced 3 _} l FMNHry l b “l 8 6 ur- may f) 4 pts. Why does eytosolic NADH produce fewer ATP molecules in oxidative phosphorylation? g) 4 pts. You have isolated fragments of the mitochondrial inner membrane. You believe that one or more of the ET complexes are present. You do an experiment and find that neither succinate or NADH is oxidized in the presence of CoQ. However, the following reaction is catalyzed: 2 Cyt c (Fefl) + 1/2 oz +2 H --—> 2 Cyt c (F63) + H20 Which respiratory complex(s) are present. 2. (23 pts) glucose l glucose—6P J. fructose-6-P l fructosel ,6 bis-phosphate »L l glyceraldehyde dihydroxyacetone -3iP (- phosphate 1,3 bisphosphoglycerate J. 3-P-glycerate l 2-P glycerate l phosphoenolpyruvate l pyruvate l lactate a) On the glycolytic pathway shown, number the steps for gluconeogenesis using lactate as the starting material. Indicate any additional steps necessary (include substrates, enzymes, co- factors or co-substrates). 0.5 pts each on scheme b) Indicate which steps in gluconeogenesis are regulated. Multiple choice ( 1 pt each) c) Both glycogenesis and glycogenolysis are controlled primarily by the interplay between the two hormones insulin and A. Epinephrine B. Glucagon C. Estrogen D. Testosterone E. Serotonin d). Which of the following is required for the conversion of UDP-glucose to glycogen? A. Glycogen synthase B. Branching enzyme C. Glucose pho sphorlyase D. Debranching enzyme E. Both A and B are correct e). Gluconeogenesis occurs primarily in the A. Brain B. Muscle C. Liver D. Heart E. Pancreas f). Gluconeogenesis is stimulated by high concentrations of which of the following compounds? A. Lactate B. Glycerol C. Amino acids D. Both A and B are correct. B. All of the above are correct. True or False (1 pt each) g. When lactate from the cytoplasm is the starting material for gluconeogenesis it is converted to pyruvate in the mitochondria. h. Pyruvate is transported into the mitochondria, but lactate is not. i. Pyruvate is converted to oxaloacetate in the mitochondria. j. Oxaloacetate in the mitochondria is converted to either phosphoenolpyruvate, aspartate or malate for transport back to the cytoplasm for gluconeogenesis. k. Aspartate is converted to pyruvate in the cytoplasm for gluconeogenesis. l. The conversion of oxaloacetate to malate requires mitochondrial NADH and the conversion of malate back to oxaloacetate requires cytosolic NAD+. 1n. (2 pts) Caffeine inhibits glycogen phosphorylase a and inhibits CAMP diesterases. Given what you know about signal transduction and glycogen metabolism can you explain why caffeine acts as a stimulant based solely on its effects on glycogen metabolism? 3. (26 pts) a) Fill in the missing portions. Boxes 1-4 are for the type of CHEMICAL reaction, not the enzyme name. Boxes 5-13 are for reactants or co-factors, names only. 0.5 pt each. 0 . ll R —-CH2—— CIIE—Cllg—Cw S-COA 13 o H R—CHz—C- s—cm Fart ac lCoA ‘~ \ y y I a mo \ 12 \ (4) i E FADE-l? 0 o o I] II H H R~CHJHC~-CH2—C—S-C0A R—CHz—CZE—C—S-COA 3—Ketoacyl CoA trans—az—Euoyl CoA l 1 :1 [E3 J ' g {A 9 H O I ll 1 | 0 chnl—cmcuz— us—COA OH L-3—Hydmxyacyl CUA Fill in the blanks ( 1 pt each) and answer any questions: b) Fatty acids require a net total of (give a #) molecules of to be activated before entry into oxidation. Briefly explain your answer (2 pts). c) Activated fatty acids must be transported to by way of as a carrier molecule before oxidation may occur. d) For every round of oxidation carbons are removed in the form of e) In the case of odd chain fatty acids at the last step of oxidation, and are the products. One of the these products must be further metabolized using two cofactors and . The final product is and enters the pathway. f) (2 pts) What is the primary method of regulation of oxidation of fatty acids? g) (4 pts) Defects in B-oxidation of fatty acids were presented in the posters. Which steps were affected and what was the metabolic outcome of these defects? 4. Truel’False (1 pt each) Epinephrine activates a signaling pathway that mobilizes glycogen breakdown, degradation of triacylglycerides to fatty acids and inhibits gluconeogenesis. The Cori cycle is an important link between lactate produced in muscles and glucose synthesis in the brain. The pentose phosphate pathway consists of two stages, one of these is an Oxidative stage that produces NADPH for fatty acid synthesis and deoxyribonucleotide synthesis. The pentose phOSphate pathway starts with 3-six carbon sugars and ends up with 6-three carbon sugars. In the pentose phosphate pathway any 5 carbon sugars not needed for nucleotide synthesis are recycled into glycolytic intermediates. 5. ( 8 pts) From the list of precursors indicate which are _ _ aspartate required for the synthes1s of: glutamate asparagine glutamine alanine methionine COJHCO; N2 , _ _ , biotin as a methyl donor NOTE: This 15 not a trlck questrou, choose only tetrahydmfolate as a methyl the most IMMEDIATE precursors in the synthesis donor PURINES PYRIMIDINES :T‘UCPHOQAOO‘N l-i. .—I. of purines or pyrimidines. k glycine _ . 1 ribose-S-phosphate The number of incorrect answers Wlll be m glucose_6_phosphate subtracted from the number of correct answers. n fructosc_6_phosphate 6. Fill in the blanks (1 pt each) and answer any questions. a. is the co-factor necessary for transamination reaction. This cofactor is bound to the enzyme through a residue. b. is the most common donor of the amino group in transamination reactions. c. Write out a general formula for transamination reactions (3 pts). d. (2 pt) What is the product of transamination of pyruvate? e. (4 pts) Explain the importance of the glucose-alanine cycle. (5 pts) Briefly define or explain the following: uncoupling Q-cycle lipoprotein glucogenic vs. ketogenic e. aliopurinol The following questions are over some of the material presented in class and in the poster sessions. (1 pt each question) 8. All of the following statements concerning folic acid are true except: A. N5,Nm-rnethylene THF is a product of the cleavage of glycine. B. mmpo ow>s U E. Vitamin B12 is required for the Ns—methyl THF dependent conversion of homocysteine to methionine. N‘O-forrnyl THF, CO2 and aspartate are precursors in the synthesis of hypoxanthine. Folic acid is a B vitamin. Folic acid requires intrinsic factor for its absorption in the intestine. Folic acid is implicated in neural tube defects. All of the following statement about the purine salvage pathways are true except: . The purine salvage pathway saves the cell energy Lesch-Nyhan syndrome is due to a defect in the salvage of guanine and hypoxanthine Excessive purine biosynthesis or defects in purine catabolism result in excess uric acid causing gout . A defect in the enzyme that deaminates adenosine results in the inability of bone marrow to make T and B cells Cytosine is degraded to uric acid. 10. Formation of cholesterol deposits in arteries has been linked to the following except: A. Lack of LDL receptors B. Excessive production of homocysteine C. Lack of serotonin receptors D. Lack of apolipOprotein A-I in HDL E. Excessive consumption of fatty acids in the form of french fries 11. The following statements about amino acid metabolism are true except: A. Methionine synthesis requires the transfer of a methyl group to homocysteine by cobalamine. Tyrosine is synthesized from phenylalanine by hydroxylation. Degradation of branched chain amino acids requires an enzyme complex that contains lipoic acid. 0.55 D. Ornithine and citrulline are amino acids E. The purpose of the urea cycle is to remove excess ammonia from degradation of amino acids F. Carbamyl phosphate used in the urea cycle is the same used in nucleotide biosynthesis Extra Credit (3 pts) What was the most interesting or important biochemical fact you learned this semester? 10 ...
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CH369 exam3f99 - a???“ 1. (1? pts) On the outline of...

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