中山大学生化上考试往年试题完整版.doc

中山大学生命科学学院试卷（考试时间：2008-01-10，15：00 17：00）生物化学I（2007年秋季学期, A卷）专业(班级)： 姓名： 学号： 任课教师：郑利民 李国富 阅卷教师： 题号IIIIIIIVV合计分数警示中山大学授予学士学位工作细则第六条：“考试作弊不授予学士学位”。 I.填空题（共15小题，每小题2分，共30分）1. pK1、pK2、pKR分别代表氨基酸的a羧基、a氨基和侧链基团的解离情况，则Lys的pI ，Glu的pI .2. 维持蛋白质高级结构的非共价作用力包括氢键、 、 等.3. 根据蛋白质的二级结构组成，可将其分为all b、all a、 、 四类.4. a角蛋白的二级结构是 ，含有大量带疏水侧链的氨基酸；同时，a角蛋白还含有丰富的极性侧链氨基酸 .5. 蛋白质体内折叠需要的辅助分子有分子伴侣、 、 等.6. 被解析晶体结构的第一个蛋白是 ，其辅基是 .7. 在抗体基本结构的标示中，H和L代表 ，V和C代表 .8. 生物大分子结构测定的主要方法有 、 、电子显微镜等.9. 酶在体内的活性调节方式有 、 、酶的切割激活等.10. 列举两个蛋白水解酶家族 、 .11. 糖原和淀粉由葡萄糖通过 糖苷键连接；纤维素由葡萄糖通过 糖苷键连接.12. 寡糖与蛋白的O连接指 ，N连接指 ；13. 指示某段DNA处于功能活动状态的特殊结构有Z-DNA、 、 等.14. 在Sanger法DNA自动测序中，荧光基团可以标记在 上或标记在 上.15. 结构性脂类包括磷脂、糖脂和 ，有些磷脂、糖脂的骨架不是甘油而是 ，因此这部分脂又被称为鞘脂.II. 简答题（每小题6分，共30分，1-5题选做3题，6-9题选做2题）1. 有那些氨基酸残基在蛋白质功能中发挥重要作用？列举三例.2. 为什么酶能降低反应的活化能？3. 解释Ach受体通道的工作机制（可结合草图说明）.4. 细胞膜表面的寡（多）糖有何生物学功能?5. 物质跨膜运输的类型有那些？6. 根据肌肉收缩的分子机制，解释“尸僵”现象.7. 朊病毒引起的疾病又称为“蛋白质构象病”，请从蛋白质折叠的热力学角度解释它的致病机理.8. 有一多肽，其一级结构可能是直线式的也可能是闭环式的. 你如何尽可能简单地做出鉴别?9. 一级结构决定三维结构，那么如何理解三维结构相似（同）的同源蛋白一级结构的较大差别？III. A protein of unknown structure has been purified and is subjected to gel filtration chromatography under different conditions, with the following results: 1) Chromatography under native conditions suggests a molecular weight of 240,000 from comparison to standards of known molecular weight chromatographed on the same column; 2) Chromatography in the presence of 5 M urea yields a single protein peak corresponding to a M.W. of 60,000 from comparison to standards of known molecular weight chromatographed on the same column in urea.1. What information do the results of (1) and (2) give about the structure of the protein? Describe the structure as completely as the data permit;2. On an SDS polyacrylamide gel, the pure protein shows two stained bands. The relative mobilities of those 2 unknown bands are shown on the plot below as open circles (O), with the mobilities of 5 known polypeptide standards of M.W. 15,000; 20,000; 30,000, 40,000 and 50,000. Given the results of the SDS gel, how would you alter your description of the protein structure from the description you gave in part 1? Be as specific as you can about your revised description of the structure, and explain the reason for the altered description.BAIV. Lysozyme destroys the cell wall of bacteria by catalyzing the hydrolysis of 1,4-linkages between N-acetylmuramic acid (NAM) and N-acetyl-D-glucosamine (NAG) residues in a peptidoglycan. Six hexoses of the substrate fit into the active site of lysozyme, a deep cleft across part of the globular protein surface this cleft. Figure A shows the hydrolytic process of 1,4-linkages between NAM and NAG and figure B shows the pH-activity profile of lysozyme. Please calculate the ratio of the enzyme molecules which really work at pH 3.8, 5.2, 6.6 to all enzyme molecules, and explain figure B according to your calculation (pH = pKa + lg(A-/HA)； pKaGlu = 5.9, pKaAsp = 4.5；102.1126，100.75).生物化学I（2006年秋季学期, A卷）专业(班级)： 姓名： 学号： 任课教师：郑利民 李国富 阅卷教师： 题号IIIIIIIVVVI合计分数警示中山大学授予学士学位工作细则第六条：“考试作弊不授予学士学位”。 I.简答题（共25小题，每小题4分，超过50分以50分计入总分）1哪些标准氨基酸含两个手性碳原子？写出它们的Fisher投影式。（4）2为什么SDS变性电泳可以估算蛋白质的分子量？（4）3Mass spectroscopy在生物大分子研究中有什么应用？（4）4a-Keratin、Collagen、Silk fibroin的二级结构和氨基酸组成有何特点？（4）5根据二级结构的组成和排列可将蛋白质结构分为哪些类型？（4）6蛋白质in vivo条件下的折叠有哪些辅助因子？（4）7蛋白质在与其他分子的相互作用中发挥作用，这种相互作用有何特点？（4）8哪些因素可以导致Hemoglobin与O2的亲和力增加？（4）9图示抗体的一般结构（包括结构域及可能的二硫键）。（4）10构成肌肉粗丝和细丝的蛋白分子有哪些，各有什么功能？（4）11写出蛋白质氨基酸测序的基本步骤。（4）12什么是酶催化的过渡态理论？列出你所知道的支持证据？（4）13酶的可逆抑制剂有几类？它们的抑制动力学各有何特点？（4）14酶在体内的活性是如何受到调控的？（4）15淀粉与纤维素的结构有何区别？（4）16细胞膜表面的Glycoprotein和Glycolipid有哪些生物学功能？（4）17细胞内的DNA可能会出现哪些异常结构，他们有什么生物学意义？（4）18膜脂的分类及其结构特点（4）19生物膜的功能有哪些？（4）20膜蛋白以哪些方式参与生物膜的构成？（4）21图示secondary active transport，uniport，symport，antiport. （4）22Acetylcholine receptor通道是如何控制开关的？（4）23K离子通道是如何对通过的离子进行选择的？（4）24膜电位是怎样控制Na通道开关的（可图示并说明）？（4）25Ca2+泵和Na+-K+泵的异同点。（4）II. You have a crude lysate sample containing a mixture of six proteins (1, 2, 3, 4, 5, and -galactosidase). Some characteristics of these proteins are shown in the table below. Give an available procedure of purifying -galactosidase. (10 pts)ProteinConcentration of ammonium sulfate required for precipitationMolecular Weight (kDa)Isoelectric point (pI)145%383.7280%224.8365%145.3420%756.8530%559.5b-galactosidase45%1155.3III. You are working on a compound as a potential drug that inhibits an overproduced enzyme whose uncontrolled activity leads to uncontrolled cell proliferation (cancer). A steady-state kinetic analysis of the enzyme-catalyzed reaction was carried out, with velocities measured as a function of the concentration of the substrate in the absence and in the presence of 10 nM inhibitor. The results of the kinetics experiment are plotted for you below. Please answer the following questions. (10 pts)1. What type of inhibitor is this compound (be as specific as you can)? Show the diagram of the inhibitors mechanism (by E denoting enzyme, S denoting substrate, I denoting inhibitor; for example: ).2. Calculate the Km, Kcat in the absence of inhibitor andKmapp, Kcatapp in the presence of inhibitor (app denoting apparent. The total concentration of enzyme is 2nM).3. Calculate the inhibitor constant KI.IV. Lysozyme destroys the cell wall of bacteria by catalyzing the hydrolysis of 1,4-linkages between N-acetylmuramic acid (NAM) and N-acetyl-D-glucosamine (NAG) residues in a peptidoglycan (figure A). Figure B shows the binding of the peptidoglycan to the active site of lysozyme, a deep cleft across part of the globular protein surface. Six hexoses of the substrate fit into this cleft. Figure C shows the hydrolytic process of 1,4-linkages between NAM and NAG and figure D shows the pH-activity profile of lysozyme. Please answer the following questions. (10 pts)1. What can you talk about the figure B in accord with the enzymatic mechanism?2. What can you talk about the figure C in accord with the enzymatic mechanism?3. Calculate the ratio of the enzyme molecules which really work at pH3.8, 5.2, 6.6 to all enzyme molecules, and explain figure D according to your calculation (pH = pKa + lg(A-/HA)； pKaGlu = 5.9, pKaAsp = 4.5；102.1126，100.75).Figure AFigure BFigure CFigure DName Class Score Biochemistry (I) Final Exam (fall, 2004)NOTE: You must write your answer on the answer sheet!Part I: For the following multiple choice questions, one answer is most appropriate (2.518 = 45 points).1. With regard to amino acids, which statement is false?A) Amino acids can act as proton donors and acceptors.B) All amino acids discovered in organism are L enantiomers.C) An L amino acid can be Dextrorotary.D) A conjugate acid/base pair is at its greatest buffering capacity when the pH equals its pK.E) Non-standard amino acids can be found in the hydrolysis product of a protein.2. A mixture of Ala, Arg, and Asp in a pH 5.5 buffer was placed on a cation exchange column (the column is negatively charged) and eluted with the same buffer. What is the order of elution from the column? Use these pKa values: terminal COOH - 2, terminal NH3+- 9, R-amino - 10, R-COOH - 3A) Arg, Ala then AspB) Arg, Asp then AlaC) Asp, Ala then ArgD) Asp, Arg then AspE) Ala, Asp then Arg3. Proteins can be chromatographically separated by their different A) Charge.B) Molecular weight.C) Hydrophobicity.D) Affinity for other molecules.E) All of above.4. A peptide was found to have a molecular mass of about 650 and upon hydrolysis produced Ala, Cys, Lys, Phe, and Val in a 1:1:1:1:1 ratio. The peptide upon treatment with Sangers reagent (FDNB) produced NP-Cys and exposure to carboxypeptidase produced valine. Chymotrypsin treatment of the peptide produced a dipeptide that contained sulfur and has a UV absorbance, and a tripeptide. Exposure of the peptide to trypsin produced a dipeptide and a tripeptide. The sequence of the peptide isA) val-ala-lys-phe-cysB) cys-lys-phe-ala-valC) cys-ala-lys-phe-valD) cys-phe-lys-ala-valE) val-phe-lys-ala-cys5. With regard to protein structure, which statement is false?A) The dominant force that drives a water-soluble protein to fold is hydrophobic interaction.B) The number of hydrogen bonds within a protein intends to be minimized.C) The conformations of a native protein are possibly the lowest energy state.D) The conformations of a native protein are countless.E) Disulfde bridges can increase the stability of a protein.6. Which structure is unique to collagen?A) The alpha helix.B) The double helix.C) The triple helix.D) The beta structure.E) The beta barrel.7. Which protein has quaternary structure?A) Insulin.B) A natural antibody.C) Chymotrypsin.D) Aspartate transcarbamoylase (ATCase).E) Myoglobin.8. Which of the following are broad themes used in discussing enzyme reaction mechanisms?A) Proximity stabilizationB) Transition state stabilizationC) Acid-base catalysisD) Covalent catalysisE) All of the above9. Under physiological conditions, which of the following processes is not an important method for regulating the activity of enzymes?A) PhosphorylationB) Temperature changesC) AdenylationD) Allosteric regulationE) Protein processing10. The conversion of glucose to pyruvate is a multistep process requiring ten enzymes. If a mutation occurs resulting in a lack of activity for one of these enzymes, which of the following happens?A) The concentration of the metabolic intermediate which is the substrate of the missing enzyme is likely to increase and accumulateB) The concentration of pyruvate will increaseC) The cell will produce more of the other nine enzymes to maintain steady stateD) The concentration of the metabolic intermediate which is the product of the missing enzyme will decreaseE) A and D11. Indicate which is true about enzymes.A) Enzymes are permanently changed during the conversion of substrate into product.B) Enzymes interact irreversibly with their substrates.C) Enzymes change the energy difference between substrates and products.D) Enzymes reduce the energy of activation for the conversion of reactant into product.E) Enzymes increase the energy content of the products.12. Consider a reaction as follows:A + B C + D, G0 = +10.0 Kj/molHow can this reaction go forward?A) Coupling of this reaction to a highly exergonic reaction through a common intermediate.B) Immediate removal of the products.C) Addition of the appropriate enzyme.D) A and B.E) All of the above.13. Which statement is not true of enzyme inhibitors? A) A competitive inhibitor binds the active site of the enzyme. B) Allosteric enzymes exhibit Michaelis-Menton kinetics. C) A noncompetitive enzyme binds elsewhere than the active site. D) Noncompetitive inhibitors cannot be completely overcome by adding more substrate. E) Competitive inhibition can be completely overcome by adding more substrate.14. You could most dramatically destabilize a duplex DNA molecule in an aqueous solution byA) Decreasing the temperature.B) Decreasing the concentration of salt.C) Decreasing the concentration of organic solvents.D) Adjusting the pH to a value near 7.E) Adding a detergent.15. With regard to DNA, which statement is false?A) Triple helix and tetraplex tend to appear at sites where replication, recombination or transcription is initiated or regulated.B) Hydrogen bonds are the only force to stabilize DNA structure.C) The absorbance of DNA at 260 nm will rise when it is denatured.D) Z-DNA tracts may play an role in the regulation of the expression of some genes or in genetic recombination.E) B-DNA is the most stable structure in physiological condition.16. With regard to biological membrane, which statement is false?A) The ratio of proteins to lipids is various in different membranes.B) The membrane with more proteins has more complicated function than that with fewer proteins. C) Each membrane has a characteristic composition of lipids.D) Lipids symmetrically distribute in the two leaflets of a membrane.E) The flip-flop movement of lipids is done by a kind of enzyme.17. Which of the following statements are true about the interactions between substrate and active site? You can assume that the catalysis goes to completion. Catalytic residues can be affected by pH The majority of bonds in E-S interactions are covalent bonds such as disulfide and peptide bonds The components of a mixture of the two mirror-image isomers of a compound, called a racemic mixture, will be acted upon equally by an enzyme The active site can alter itself to better fit the substrate The active site is permanently altered by its interaction with substrate The substrate is permanently altered by its interaction with active site Competitive inhibitors have no affect on the active siteA) , , B) , , C) , , D) , , E) , , 18. Which of the following statements refer to glycogen (G) and which refer to cellulose (C)? Contains beta-1,4 glycosidic bonds Cannot be digested by mammalian enzymes Straight-chain molecule of high tensile strength Contains alpha 1,6-glycosidic bonds Branched molecule Used as a structural component Used as a nutritional storage moleculeA) G= , , ; C= , , , B) G= , , ; C= , , , C) G= , , , ; C= , , D) G= , ; C= , , , , E) G= , , ; C= , , , Part II: According to the figures and conditions provided, fill the blanks (Fewer have two or more answers, 55 points).19. Protein secondary structures and their organization (5 points).A) Parallel b-pleated sheet;B) Antiparallel b-pleated sheet;C) Residues of Pro and Gly;D) Residues of Pro and Val;E) Residues of hydrophilic amino acids;F) Residues of hydrophobic amino acids;G) Residue of Arg, Lys, or His;H) Residue of Asp, or Glu.a) One domain of the protein is composed of b) What amino acids are frequently found in 5 c) If the residues at 6 is positively charged, then the residue at 7 is best d) What residues occur mostly at 1 and 2? e) What residues occur mostly at 3 and 4? 20. Several oxygen dissociation curves are shown in the following figure. (5 points).Assume that curve C corresponds to purified hemoglobin placed in a solution containing physiological concentrations of CO2 and BPG at a pH of 7.0. Below, indicate which of the curves reflects the changes noted in physiological conditions by placing the curve # on the lines below (Use only one curve choice/physiological change):a. Decreased CO2 concentration_ b. Increase BPG concentration_ c. Dissociation of hemoglobin into subunits d. A mutation that eliminates ion pairs that stabilize the T or deoxygenated state e. Fetal hemoglobin or a mutation which increase binding affinity for oxygen 21. Supersecondary structure of proteins (5 points).A) b-a-b Loop; B) Greek Key; C) a-a Corner;D) Right-handed connection between b strands; E) Not observed; F) Very rare. a. b. c. D d. e. f. 22. Protein classification (5 points).A) All a; B) All b: C) a/b; D) a+b; E) Superfamily; F) Species a. A d. e. f. 23. Kinetics of enzyme inhibition or double-substrate reaction (5 points).a. Competitive inhibition A b. Non-competitive inhibition c. Uncompetitive inhibition d. Mixed competitive inhibition If S2 and substitute for I and respectively, then:e. Double-substrate enzyme reaction involving a ternary complex f. Double-substrate enzyme reaction with a ping-pong mechanism 24. Structure about Nucleotides and DNA (5 points) a. Exo-2 / Endo-2configuration of ribose b. Exo-3 / Endo-3configuration of ribose c. Hoogsteen Pairs d. Can form cruciform structure e. Can form H-DNA 25. Biomembrane lipids (5 points)a. Sphingolipids b. Phospholipase A1 c. Phospholipase A2 d. Phosphol