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Spring 2008 Exam 3

Spring 2008 Exam 3 - BBMB 40411 ~ Exam 3(Spring 2008 l...

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Unformatted text preview: BBMB 40411 ~ Exam 3 (Spring 2008) l. Eversion 1s the process by which: A l a) channels change their conformation to the open state . 1)) pumps change conformation exposing their binding sites to different sides of the membrane 1 c) the 'ball-and—chain' model works for inactivating the open state of" Ion channels d) electrochemical impulses are propagated do'wn neurons What is the primary function of the selectivity filter in ion channels? a) it closes the'chann'el pore after ion passage 1)) it determines the preference for a particular ion 0) it limits the number of ions passing through the channel; at) alt'ot‘the'above Which of the following most accurately describes why voltagefgated channels are not open the entire time their threshold voltage has been exceeded? a) spontaneous closure 1)} the ball-and-ehain model c) to avoid neural over—stimulation . , (i) so that electric rays won't shock themselves ., A. Neural Na+ and K+ channels are examples of a) aversion in channels b) iigandegated channels 0) pumps creating electrochemical gradients d) non-selective channels e) none of the above The acetylcholine receptor is an example of a: ‘ a) ligandugated channel b) voltage-gated channel 8) tyrosine kinase , d) P—type pump You are trying to determine if a conserved lysine in your channel of interest is important in its ion selectivity Which of the following experimental strategies would be. most likely to tell you what you want to know: a) site-directed mntagenesis followed by patch-clamp conductance measurements b) site-directed mutagenesis followed by size—exclusion chromatography ' c) size—exclusion chromatography followed by site-directed mutagenesis d) detergent solubili'zation followed by gel electrophoresis 7. How do organisms most directly generally sense change in their environment? a) ligand binding to cell surface receptors b) change of conformation' in receptor structure c) nuclear honnone binding to cytoplasmic receptbrs 8. What is a key similarity betWeen the active forms at heterotrimen‘c and small G—proteins'? Bothare active with GTP bound. Both bind and'acti'vat'e various effectbr'pi‘ote‘ins. 9. Tyrosine kinase receptors: a) dimerize and cross-phosphorylate b) are often coupled to small G-proteins c) directly act to replace GDP with GTP d) A and B ' c) all of the above 10. Serpentine receptors a) contain multiple membrane-spanning helices b) are coupled to heterotrimeric G—proteins ‘ c) act to replace GDP with GTP d) A and C c) All of these i) None of these i 1. Adaptor proteins act in signal transduction to a) amplify the signal by phosphorylating other proteins 1)) mediate interactions between components of the pathway c) bind and inactivate receptors d) directly bind and respond to extracellular ligands 12. Calmodulin binds and activates effectors such as GM kinase in response to a) diacylglycerol b} cyclic AMP c)'- calcium- d_) cyclic GMP e) steroid borinones 13. Protein kinase A (PKA) is a)’ affected by cyclic AMP only under unusual circumstances. b) competitively inhibited by cyclic AMP. c) allosterically inhibited by cyclic AMP. d) allosterically activated by cyclic AMP. e) activated'by covalent attachment of cyclic AMP. 15. .14 Reaction pathways that transtorm incl molecules into _.ceilalm: energy are most properly termed. a) metabolic b) anabolic c) catabolic d) amphibolic c) all of these What explains the ability of activated carriers to stably carry h1gh-energy bonds? a) electrostatic repulsion 1n the reactant _ - . i b) stabilization of products by ionization. c) high activation energy of hydrolysis d) stabilization of products by solvation e) stabilization of products by extra resonanCe forms 16. The energy charge state is tightly controlled In metabolism, this IS often reflected at the r 17. 18'. 19. effect ofATP and/or the eficct of ADP on enzymes a) activating, inhibitory, hydroiytic b) inhibitory, activating, catabolic c) inhibitory, activating, anabolic d) activating, inhibitory, catabolic e) allosteric, inhibitory, anabolic Isozymes involved 111 mammalian metabolism: 1 _ a) differ' in biochemical details, contributing to metabolic specialization b) catalyze different reactions 1:) are the same, to ensure uniform metabolism throughout the. organism A d) create electrochemical gradients across the plasma membrane Which of the following is away “in which metabolic processes can be regulated? . _. a) Control of the ambunt of enzyme - b) Control of the catalytic activities of enzymes 0) Control of the flux of substrates . d) Control of the accessibility of substrates c) All of these What is the fundamental chemical process that underlies chemotrophic metaboiisin? ’- Oxidation of carbon '20. What is the metabolic purpose of phosphorylating glucose in the cytosol: a) to destabilize glucose and facilitate the next series of metabolic steps; 1)) glucose 6-phosphate is trapped in the cell. c) to make it more soluble. d) All of the above 9.) A and'B only 21. Phosphofructose kinase is heavily regulated because: a) it catalyzes the first step in glycolysis. b) it catalyzes the only irreversible step in glycolysis. c) it catalyzes the committed step in glycolysis; d) it catalyzes an intermediate irreversible step in glycolys'is. 22. Gluconeogenesis is not a reversal of glycolysis but a) requires the input of more energy than is released by glchlysis. ' b) uses some of the same enzymes as glycolysis. c) is separated fi‘o‘m glycdlysis by compartmentahzation (in eukaryotes). d) all of the above. 3) A and C 23. Glycolysis results in a redox imbalance that can be restored by a) fermentation of pyruvate to lactate. b) fermentation of pyruvate to ethanol c) oxidation of pyruVate to (302 and water (i. e. oxidative phosphorylatiOa) d) any of these. e) none of these 24. Glucose transporters in mammals - a) all have the same affinity for glucose. 19) transport both glucose and glucose— —6- ”phosphate c) differ between Various tiSs‘ues, contributing to metabofi'c speciahZatienfi (1) do not have any role 1n cancer. , - ' 25. Which carrier is used in bothrglycolysis and the TCA Cycle in mammals? a) biotin ' ' ' " ' b) NAD+ c) FAD d) CoA c) all of these 26. What are the products of the pyruvate dehydrogenase complex? a) NADH, acetyl CoA b) FADHZ, succinyl CoA c) NADH, (A)TP d) FADH2, acetyl CoA 27. The full TCA cycle specifically a) oxidizes pyruvate to C02 and generates NADH and (A)TP- b) oxidizes acetyl CoA to C02 and generates NADH and (A)TP 0) produces biosynth'etic precursors cl) A and C e) B and C 28. Pymvate dehydrogenase lS controiled by the energy state of the cell, which of the following activates this key enzyme? a) ADP b) ATP c) NADI-I d) acetyl—CoA e) none of these 29 Which (to-factor. or- carrier is involved in all the fimctions of the anketo acid (i e. pytuvate/a— ketogluiarate) dehydmgenase complexes? - - - a) thiamine pyrophosphate (TPP) b) lip‘oami'de c) FAD d) NAB+ e) CoA 30. What directly drives the production of the highsenergy phosphate bond' in the TCA- cycle? a) oxidative- deearboxylation . -- l1) hydrolysis of a thioester bond , ‘ - c) the electron transfer potential of the two- high energy electrons' 1n FADH2 ‘ d) the electron transfer potential of the two high energy electrons 1n NADH e) none of these 31. The cycle enables to subsist on acetate. a) TCA; bacteria and plants b) TCA;-animals and plants ' . c) glyoxylate; animals and plants d) glyoxylate; bacteria and plants 32. Which of the following acts as both a carrier and co‘factor 1n the electron transport chain? a) Q h) Fe-S c) FAD d) Cu e) none of the above” 33. The protons in QH; are from the a) acetyI-Co'A; matrix and are put in the b) intermembrane space/cytosol; matrix c) matrix; outer membrane d) matrix; intermembrane space/c‘ytosol' \. 34. How many protons are pumped across the membrane by complexes I, II, III, and IV in the electron transport chain? . . 35. In an ATP synthase with a o ring composed of 12 c subimits, how many protons are required to produce one molecule of ATP? , a) 3.33 b) 4 c) 6 d) 12 36. Why do heart and liver cells typically make more ATP/giucose than muscle cells? a) they use the ATPIADP transporter b) they use the glycerol-S-phosphate shuttle for glycoiytically generated NADH. c) these tissues are carrying out gluconeogenesi's - (1) they use the malate—aspartate shuttle for glycolytically generated NADH e) they create a steeper proton elecn'ochemiCal gradient 37 Besides the ATP synthese, list two other biological processes that can be driven by proton electrOchemic'al gradients? - Heat generation, N ADPH synthesis, active tran5po'rt, flagella-rotation ...
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