课程名称︰生化 课程性质︰必修 课程教师︰吴世雄 开课学院：理学院 开课系所︰化学系 考试日期（年月日）︰2011/4/12 考试时限（分钟）：2小时 是否需发放奖励金：是 （如未明确表示，则不予发放） Midterm answer Part I (44%) 1. AEEBD 6. CBDCD 11. ACBDD 16. ACCBCAD Part II (24%) 23. esgjxi 29. wyhbnm Part III (8%) 35.48 36.7.2 37.555 38.1.8 Part IV (6%) H-bond, electrostatic force(ionic bond or salt bridge), Van Deer Waal force, Disulfide bond , Metal-ion coordination, Hydrophobic force. Part V. (5%) Val-Leu-Gly-Met-Ser-Arg-Asn-Thr-Trp-Met-Ile-Lys-Gly-Tyr-Met-Gln-Phe Part VI. 请参考 textbook chapter 6. review exercise No.55. answer. Part VII. 1. 真核生物比原核生物拥有1. Nucleus, 使DNA present but separate from rest of cell. (2%) 2 双层膜构造的胞器, 提高整体效率, and could be larger without area-to-volume consideration being critical because of compartmentalization.(3%) 2. 1. X-ray 2. 2D-NMR 3.homology modeling->comparative modeling of proteins refers to constructing an protein from its amino acids sequence. 4. Cryo-EM. (第一个3% 3% 4% 有写出三个十分) part1 single choice 1.in the reaction catalyzed by aspartate transcarbamoylase, a graph in which the rate is plotted against the concentration of substrate a. is sigmoidal, characteristic of an allosteric enzyme b. shows that noncooperative kinetics are observed d.is hyperbolic, characteristic of a nonallosteric enzyme 2.what is the major force that drives nonpolar substrates out of aqueous solution? a. increased enthalpy of hydrophobic bonds formed between solute molecules b.decreased entropy of newly organized solute molecules c.increased entropy of newly organized solute molecules d.increased enthalpy of H-bonds in the solvent water e.incresed entropy of solvent water 3.vitamin C(ascorbic acid) prevents scurvy because it a.is involved in the formation of the proper beta-sheet structure of collagen b.is involved in the metabolism of heme used in hemoglobin c.encourages the formation of disulfide linkages in collagen d.is an unusual amino acid found in the primary structure of collagen e.is used to hydroxylate proteins in the primary structure of collagen 4.the active site of chymotrypsin contains all of the following, except a. histidine residue b. a Mg2+ c.hydrophobic pocket to bind the substrate d.serine residue e.all of these are in the acitve site of chymotrypsin 5. which of the following can result in protein denaturation? a. heat b. extreme of pH c.detergent d. all of the above 6.which of the following is not a difference between the concerted model and the sequential model of allosteric enzyme? a. the sequential model allows for different subunits to be in different conformations while the concerted model does not b. negative cooperativity can be explained by the sequential model but not by the concerted model c. positive cooperativity can be explained by the sequential model but not by the concerted model d. the sequential model is explained better by considering the induced-fit model of substrate binding, whereas the concerted model focuses on perturbing the equilibrium between the T and R forms 7. buffering capacity refers to a. the effectiveness of commercial antacids b. the extent to which a buffer solution can counteract the effect of added acid or base c. the pH of a buffer solution d. the molecular weight of the substance used as a buffer 8.competitive inhibitors have this effect: a. modifying the Km value b. changing the value for Vmax c. interfering with substrate binding d. this type of inhibitor both changes the Km and interferes with substrate binding 9.when SDS electrophoretic separation are done based on molecular weight, the distance that a molecule moves can be graphed as a straight line when compared to a. the MW of the proteins b. the negative of the MW of the proteins c.the log of the MW of the proteins 10. quaternary structure is associated with a. the overall shape of the polypeptide chain b. the sum of secondary and tertiary interactions c. simple proteins with only one subunit d. the relative orientation of one polypeptide to another polypeptide in a multisubunit protein 11.which of the following correctly lists the isoelctric pH's of asp, asn, and arg from lowest to highest a. D N R b. D R N c. R N D d. R D N e. N R D 12. 2 amino acid frequently found in reverse turns are a. tyrosine and tryptophan b. serine and threonine c. glycine and proline d. leucine and isoleucine 13. the peptide bond a. is formed by elimination of water between 2 amino acids b. limits the possible orientations of the peptide backbone in a protein c. has acidic and basic characteristics 14. in the alpha-helix a. there are no hydrogen bonds b. the peptide chain is fully extended c. the peptide chain bends back on itself d. there are hydrogen bonds parallel to the helix axis 15. the Michaelis constant is a. related to the molecular weight of the enzyme b. a measure of the resistance of the enzyme to denaturation c. a reflection of the percentage of polar amino acids in the enzyme d. a measure of how tightly the substrate is bound to the enzyme 16. the binding of oxygen to hemoglobin differs from the oxygen-binding behavior of myoglobin because a. oxygen binding to hemoglobin is cooperative b. oxygen binding to myoglobin is cooperative c. hemoglobin isn't an allosteric protein d. the oxygen-binding curve of hemoglobin is hyperbolic 17.in the SDS-PAGE (sodium dodecylsulfate-polyacrylamide gel electrophoresis) method, separation takes place on the basis of a. charge only, because all particles have different charges, but the same mass b. the sieving action of the gel, because all particles have the smae charge, but different masses. c. the sieving action of the gel, because all particles have approximately the same charge/mass ratio, but different masses. d. the chemical nature of the buffer used as the electrolyte. 18. according to the steady-state assumption a. the product concentration doesn't change significantly b. the substrate concentration is large and doesn't change significantly c. the concentration of enzyme-substrate complex remains constant with time d. the free enzyme concentration is always in great excess to the concentration of enzyme-substrate complex 19. under normal circumstances: a. adult Hb binds to oxygen more tightly than Mb binds b. fetal Hb binds oxygen more tightly than adult Hb. c. adult Hb binds oxygen more tightly than either fetal Hb or Mb binds d. Mb has the lowest affinity for oxygen e. more than one of these statements is correct 20. the pH profile of an enzyme can help identify specific amino acids in the active site because: a. all enzyme have a pH optimum b. only the active site amino acids can detect changes in pH c. acidic and basic amino acids are often involved in the active site and pH changes can change their ability to catalyze a reaction d. the pH optimum is always the pI of the most critical amino acids in the active site 21. a transition state analogue a. binds tightly to the enzyme b. enhances the activity of the enzyme when bound to it c. forms a complex with the enzyme that is energetically stable compared to the enzyme-substrate complex d. will bind to the enzyme by the lock-and-key mechanism rather than the inducd-fit mechanism 22. the behavior of allosteric enzymes a. does not play any role in feedback inhibition in metabolic pathways b. is strongly dependent on the presence of metal ions c. is related to their ability to hydrolyze themselves d. depends on changes in their quaternary structure on binding of substrate or inhibitors part 2 correlate the following names or terms in (A) with those in (B) A. a.histidine b.kinase c.cysteine d.DNA e.glycine f.proline g.phenylalanine h.Alzheimer's disease i.glutamic acid j.isoleucine k.arginine l.methionine m.Zn 2+ n.chaperone o.valine p.asparate q.lactic acid r. lysine s.TPCK t.Michaelis constant u.Abyzyme w.RNA x.Edman method y.protein denaturation B. 23.which amino acid has no chiral center? 24.which compound is the inhibitor of chymotrypsin? 25.which amino acid has a benzene ring in its side chain? 26.which amino acid contain 2 chiral center? 27.to determine the protein sequence 28.which amino acid would have the greatest negative charge at pH=7.0? 29.a molecule is believed to come first in nature and possesses catalytic and hereditary properties 30.a solution containing urea and beta-mercaptoethanol 31.protein misfolding in brain 32.an enzyme involves the reaction of protein phosphorylation 33.a protein can avoid protein misfold or aggregation 34.cofactor of carboxypeptide A part 3. please complete this table number how we get proteins out of the cell. (the following table is to describe the purification steps of one protein. Some numbers are missing in the table please fill them) fraction volume total total specific percent (mL) protein(mg) activity activity recovery 1.crude extract 3800 22800 2460 0.108 100 2.salt precipitate 165 2800 1190 0.425 (35) 3.ion-exchange 65 100 720 (36) 29 chromatography 4.molecular-sieve 40 14.5 (37) 38.3 23 5.immunoaffinity chromatography 6 (38) 275 152.108 11 part 4 describe what kinds of forces to maintain the tertiary structure (3-D) of protein part 5 a sample of an unknown peptide was divided into 2 aliquots. one aliquot was treated with trypsin; the other was treated with cyanogen bromide . given the following sequences (N-terminal to C-terminal) of the resulting fragments, deduce the sequence of the original peptide trypsin treatment Asn-Thr-Trp-Met-Ile-Lys Gly-Tyr-Met-Gln-Phe Val-Leu-Gly-Met-Ser-Arg cyanogen bromide treatment Gln-Phe Val-Leu-Gly-Met Ile-Lys-Gly-Tyr-Met Ser-Arg-Asn-Thr-Trp-Met part 6 draw Lineweaver-Burk plots for the behavior of an enzyme for which the following experimental data are available [S] V, no inhibitor(mmole/min) V,inbitor present mM (mmole/min) 3.0 4.58 3.66 5.0 6.40 5.12 7.0 7.72 6.18 9.0 8.72 6.98 11.0 9.50 7.60 what are the KM and Vmax values for the inhibited and uninhibited reactions? is the inhibitor competitive or noncompetitive? part 7 please describe the major differences between a prokaryote and a eukaryote. describe how the three-dimensional structure of a protein is determined. ※ 编辑: jasonfghx 来自: 140.112.115.226 (05/07 20:43) ※ 编辑: jasonfghx 来自: 140.112.7.214 (05/15 15:46)