Fall 2005 Exam 3

Fall 2005 Exam 3 - Biochemistry 404: Exam 3 1. 12/7/05...

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Unformatted text preview: Biochemistry 404: Exam 3 1. 12/7/05 Name: What is the molecular handle for many common metabolic carriers? a) NAD+ b) Flavin c) AMP d) ADP e) CoA , at the , allowing Primary metabolic processes are controlled at the molecular level by cellular level by , and at the whole organism level by adjustments over a time frame. a) hormones, compartmentalization, differential organ function, minutes to days b) allosteric effectors, compartmentalization, hormones, seconds to days c) allosteric effectors, hormones, transcription, seconds to minutes d) inhibitors, allosteric effectors, hormones, seconds to hours 6) allosteric effectors, hormones, temperature, seconds to minutes In biological metabolism every pathway must be energetically favored. a) True b) False For a hypothetical reaction A —2* B with Keq : 10'“, how many molecules of ATP would need to be hydrolyzed to ADP + Pi to shift K,q to 1010? a) one b) two c) three d) 108 Which of the following molecules carries the most energy? b)H :Hzolo‘i H C) 010F303? 0‘ HO OH H OH H OH H OH CH20P032' Serpentine receptors: a) dimerize and cross-phOSphorylate b) are coupled to heterotrirneric G-proteins c) act to replace GDP with GTP d) B and C e) all of the above What best describes why GTP is considered a ‘clock or timer' for G—proteins? a) it diffuses away after a specific time interval b) it is regulated by energy c) it is hydrolyzed to GDP and Pi d) none of the above 10. ll. 12. 13. Common themes in signal transduction include which of the following: a) conformational changes in response to ligand binding b) conformational changes in reSponse to phosphorylation c) positive feedback loops d) mechanisms to end signaling e) all of the above f) none of the above Modular signaling domains, such as the phosphotyrosine binding SH2 domain, can operate in many different pathways. This is best described as a function of: a) cross—talk between pathways ‘0) the convergence of multiple signaling pathways on a common response 0) the different specificities of related modular domains d) the inherent tendency to exhibit a uniform response (i.e. homeostasis) Which of the following is NOT a common second messenger? a) Ca2+ b) IP3 c) G3P d) CAMP a DAG Tyrosine kinase receptors: a) dimerize and cross—phosphorylate b) are often coupled to small G—proteins (2) directly act to replace GDP with GT P d) A and B c) all of the above Which of the following is the most important cancer drug target? a) growth hormone receptor b) J AK protein tyrosine kinase c) Ras d) Gms e) Rho Phospholipase C B cleaves phosphatidylinositol—4,S—bi3phosphate to generate diacylglycerol and inositol-l,4,5-trisphosphate second messengers that: a) act completely independently b) have opposing effects 0) act synergistically to amplify a response d) are both membrane bound 14. 15. 16. 17. 18. 19. 20. The production of phosphotrioses from glucose: a) requires the input of energy b) yields a net gain of energy c) is not regulated The rate determining step in glycolysis is catalyzed by: a) hexokinase b) phosphofructokinase C) phophoglycerate kinase d) pyruvate kinase When a muscle contracts aerobically, less lactic acid is formed than when it contracts anaerobically because: a) glycolysis does not occur to any significant extent under aerobic conditions b) under aerobic conditions pyruvate is oxidized by the TCA cycle rather than fermented c) the lactic acid is rapidly incorporated into lipids d) muscle is less metabolically active under aerobic conditions than anaerobic conditions The primary purpose of fermentation is to: a) produce amino acids for protein synthesis b) generate a proton gradient for ATP synthesis C) oxidize glucose to generate reduced electron carriers d) generate alcohol for beverages e) regenerate NAD+ from NADH Which of the following glycolytic enzymes does NOT catalyze an essentially irreversible reaction under typical cellular conditions? a) hexokinase b) phosphofructokinase c) phosphoglycerate kinase d) pyruvate kinase Which of the following conversions requires the most energy to reverse in gluconeogenesis? a) glucose <—> glucose—6-phosphate b) fructose-6-phosphate <—> fi‘uctose—lfi—bisphosphate c) glyceraldehyde-3-phosphate <—> 1,3—bisphosphoglycerate d) 1,3—bisphosphoglycerate «9 3-phosphoglycerate e) phosphoenolpyruvate e pyruvate The net flow of lactate from muscles to heart is a function of carriers and isozymes of which one of the following enzymes? a) pyruvate kinase b) pyruvate carboxylase c) pyruvate decarboxylase d) lactate dehydrogenase 21. 22_ 23. 24. 25. 26. 27. Substrate cycles, such as fructose-6—phosphate <-> fructose—1,6—bisph08phate: a) are futile b) generate heat c) amplify metabolic signals (Le. the effects of changing enzymatic activity) (1) B and C e) none of the above What enzyme is important in both gluconeogenesis and the TCA cycle? a) succinyl thiokinase b) pyruvate carboxylase c) lactate dehydrogenase d) phophoenolpyruvate carboxykinase e) pyruvate dehydrogenase The TCA cycle a) oxidizes pyruvate to CO2 and generates NADH and (A)TP b) oxidizes acetyl CoA to CO2 and generates NADH and (A)TP 0) produces biosynthetic precursors d) A and C e) B and C What drives the reductive fusion of acetyl CoA and oxaloacetate? a) input of high energy electrons from NADPH b) input of high energy electrons from NADH c) hydrolysis of acetyl CoA thioester linkage d) oxidative decarboxylation of oxaloacetate What are the products of the pyruvate dehydrogenase complex? a) NADH, acetyl CoA b) FADHZ, succinyl CoA c) NADH, (A)TP d) FADHZ, acetyl CoA Which co—factor or carrier is involved in all the functions of the or-keto acid dehydrogenase complexes? a) thiamine pyrophosphate (TPP) b) lipoamide c) FAD d) NAD+ e) CoA What are potential metabolic fates of the carbons in acetyl CoA? a) lipids b) CO2 c) amino acids (1) nucleotides e) all the above 28. Our brains are particularly susceptible to metabolic poisons that interfere with the TCA cycle because this organ only catabolizes . Other tissues in our bodies can also use a) glucose; fatty acids b) ATP; fatty acids c) fatty acids; glucose d) NADH; FADH2 29. What is the energy of the thioester linkage in succinyl CoA used for? a) to reduce NAD+ to NADH b) to generate a high energy phosphoryl bond 0) to reduce FAD to FADI—I2 d) to reduce Q (ubiquinol) to QH2 30. What other metabolic process utilizes several enzymes from the TCA cycle? a) glycolysis b) glyoxylate cycle (2) gluconeogenesis d) oxidative phosphorylation 31. What carrier is used to transfer high energy electrons between the TCA cycle and oxidative phosphorylation? a) NAD+ b) FAD c) Fe—S clusters d) cytochrome c e) ubiquinol (Q) 32. What carrier/co—factor is most directly involved in the proton pumping catalyzed by the respiratory electron transport chain? a) ubiquinol (Q) b) Fe—S clusters c) heme groups d) cytochrome c e) Cu (cepper) 33. Which co—factors are contained in complex I of the electron traHSport chain? a) FAD, Fe—S b) FMN, Fe-S, heme c) FMN, Fe—S, Q d) heme, Cu 6) Q, Fe—S, heme 34. How many ubiquinol molecules participate in a single Q cycle and how many protons are 35. 36. 37. 38. 39. 40. released to the cytosolic side of the mitochrondrial inner membrane? a) 2; 4 b) 3; 6 c) 3; 4 d) 4; 4 e) 4', 8 Which co—factors/carriers can hold ONLY one electron? a) Fe—S, FMN, heme, Cu b) Q, Fe—S, heme, Cu 0) Fe—S, heme, Cu d) FAD, Fe—S, heme, Cu e) Q, FMN, Fe—S, heme, Cu Which co—factors in the electron transport chain directly interact with 02? a) Fe—S and Cu b) heme and Cu c) heme and Q d) heme and Fe-S The ATP synthase rotates in steps of because of a) 120°; the number of 0 subunits in its c ring b) 180°; the heterodimeric composition of its all?) subunits c) 120°; the trimeric asscmbly of its heterodimeric Ot/B subunits d) 360°; the asymmetry of its y subunit e) 360°; the asymmetry of the single a subunit bound to the 6 ring What residue of the c subunit transmernbrane cohelix is required for proton driven rotation of the ATP synthase? a) aspartate b) glutamate c) lysine d) arginnine e) histidine What most directly drives the import of ADP and Pi into the mitochondrial matrix? a) the ATP synthase b) the TCA cycle c) glycolysis d) the respiratory electron transport chain e) the proton electrochemical gradient What is the advantage of using the glycerol-3-phosphate shuttle in muscle cells? a) it’s fast b) it bypasses complex I of the electron transport chain c) it moves metabolites in and out of the mitochondrial matrix d) it increases the efficiency of the electron transport chain ...
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Fall 2005 Exam 3 - Biochemistry 404: Exam 3 1. 12/7/05...

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