上交生化考研练习题刘建华出Test1.doc

14Chapter 1 Biochemistry: An Evolving Science这是上海交通大学生命科学学院生化刘建华老师出的本科生卷子，我因为找人弄到了，对生化题的改革有所准备，所以11年生化考的不错，起码是个三位数了，呵呵，如愿以偿地进入了上交生科院呵呵，还有很多，如果需要请QQ联系我，2519067730I Matching QuestionsUse the following to answer questions 1-10. Choose the correct answer from the list below. Not all of the answers will be used.a) uridineb) truec) DGd) thyminee) DHf) sugar-phosphate unitsg) covalenth) Archaeai) entropyj) a systemk) 3l) 2m) falsen) positiveo) negativeDNA is made from the building blocks adenine, guanine, cytosine, and _. The DNA backbone is made from repeating _. _ The number of hydrogen bonds formed between A and T. _ The number of hydrogen bonds formed between G and C. The fundamental groups of organisms include Eukarya, Bacteria, and _.The strongest bonds in molecules are _.It is that hydrogen bonds are usually stronger than covalent bonds.All matter within a defined region of space is recognized as .The DG of a spontaneous reaction in specified conditions must be . is Gibbs free energy.II Multiple Choice11. The structure of DNA described by Watson and Crick included A) a double helix. B) the sugar phosphate backbone aligned in the center of the helix. C) the base pairs that are stacked on the inside of the double helix. D) a and b. E) a and c. 12.What did Watson and Crick suggest to be significant about the base pairing found in the helix? A)It allowed the DNA to twist in a helix. B)The DNA could be circular. C)It was a mechanism for copying. D)All of the above.E)None of the above. 13.Approximately what percentage of the human genome encodes for proteins? A)50%B)90%C)10%D)3%E)None of the above.14.What gives proteins such a dominant role in biochemistry? A)the variation in protein sizes B)the ability to act as a blueprint C)their ability to self-replicate D)their ability to spontaneously fold into complex three-dimensional structures E)All of the above. 15.If the whole chain is used in a non-overlapping frame, how many amino acids are defined by this DNA sequence: ATGTTTGGACTA? A) four B) two C) twelve D) six E) three 16.What is the H+ concentration in a urine sample that has a pH of 6? A)10-6 MB)10-8 MC)106 MD)10-14 ME)8 M17.Which of the following is considered as a noncovalent bond?A)electrostatic interactions D)All of the above. B)hydrogen bonds E)None of the above. C)van der Waals interactions 18.The energies for hydrogen bonds are approximately A)400 kJ/mol. D)200 kJ/mol. B)100240 kJ/mol. E)None of the above. C)420 kJ/mol. 19.What pairs of atoms in bases are involved in hydrogen bonds? A)NH and OH D)All of the above. B)NH and SH E)None of the above. C)OH and PO 20.Typical van der Waals energies are about A)420 kJ/mol. D)All of the above. B)24 kJ/mol. E)None of the above. C)200 kJ/mol. 21.What two properties of water are important for biological interactions? A)the polarity of water D)a and c B)the density of water E)b and c C)the cohesive properties of water 22.The First Law of Thermodynamics states A)diversity is the result of gradual evolution. B)the total entropy of a system and its surroundings always increases for a spontaneous process. C)the total energy of a system and its surroundings is constant. D)light is both particle and wave. E)None of the above. 23.The Second Law of Thermodynamics states A)the total entropy of a system and its surroundings always increases for a spontaneous process. B)temperatures will always decrease. C)the total energy of a system and its surroundings is constant. D)diversity is the result of gradual evolution. E)None of the above. 24.List atoms commonly found in biological molecules that are often hydrogen-bond acceptors. A) carbon B) oxygen C) nitrogen D) b and c E) All of the above. 25.Enthalpy is defined as A)a spontaneous reaction. D)All of the above. B)the entropy of the system. E)None of the above. C)the heat content of a system. 26.If a particular reaction has a negative DG, is it likely to occur? A)Not unless energy is added to the system. B)Yes, if it is coupled to another reaction. C)Yes, it is spontaneous. D)No, it will never occur. E)Yes, if it takes place within a constrained area. 27.What happens to nonpolar molecules in water? A)They dissolve independently. D)All of the above. B)They aggregate together. E)None of the above. C)They precipitate. 28.What is the A-/HA ratio when the weak acid is in a solution one pH unit above its pKa?A)1 : 1D)2 : 1B)1 : 10E)None of the above.C)10 : 129.Why does DNA denature when the pH is raised above 9?A)Protons dissociate from guanine bases disrupting the hydrogen bonding to the other strand.B)Protons bind to guanine residues giving them additional positive charges which disrupt the hydrogen bonding to the other strand.C)Protons bind to functional groups that serve as hydrogen-bond acceptors, thus disrupting the hydrgogen bonding to the other strand.D)Protons dissociate from the phosphate groups in the backbone, which disrupts the hydrogen-bonding pattern between strands.E)None of the above.30.Stereochemistry can be easily depicted in a simple form using A)Ball-and-stick models. D)Fisher projections. B)ribbon diagrams. E)None of the above. C)Space-filling models. 31.Which of the following is the Henderson-Hasselbach equation?A)D)B)E)None of the above.C)32.What are the primary chemical components present in a phosphate buffer at pH 7.4?A)H3PO4 and PO4-3D)H2PO4- and HPO4-2B)H2PO4- and PO4-3E)H3PO4 and HPO4-2C)HPO4-2 and PO4-3Short-Answer Questions33. What are some of the medical implications of the human genome project? 34. What is the significance of hydrogen bonding in biochemical structures such as DNA? 35. What adaptation affected evolutionary diversity? 36. Describe resonance structures. 37. What is an electrostatic interaction? Give an example. 38. How is water able to be a solvent for so many biological molecules? 39. What is the net effect of many van der Waals interactions? 40. If most proteins are found surrounded by water in the cell, what type of functional groups would you expect to find on the surface of a water soluble protein? 41. How are electrostatic forces used in protein folding? 42. If the First Law of Thermodynamics is true, how can biological processes be carried out? 43. How can a cell exist if the Second Law of Thermodynamics is true? 44. Provide a simple example of entropy processes. 45. What does this equation mean:DG = DH system TDS system 0? 46. What is the significance of using DG in biochemistry? 47. What thermodynamic and free-energy changes participate in protein folding? 48. How do hydrophobic interactions aid in protein folding? 49. What are the enthalpy and entropy changes that accompany the formation of DNA double helixes from complementary single strands of DNA?50. Describe the shape of methane. Matching QuestionsUse the following to answer questions 1-10:Choose the correct answer from the list below. Not all of the answers will be used.a) l-amino acidsb) waterc) protonsd) Zwitterionse) secondary structuref) tertiary structureg) Ramachandranh) cysteinei) extracellularj) histidinek) prolinel) Sangerm) d-amino acids _ are the chiral type of amino acids found in proteins. _ are another name for dipolar molecules. Disulfide bonds are formed by pairs of _? _ is the amino acid with a pKa near neutral pH. When a peptide bond is formed, _ is also made? Proteins with extensive disulfide links likely to be found _? _ disrupts the helix because its side chain contains a unique ring structure that restricts bond rotations. _ plot allows one to investigate the likely orientation of certain amino acid pairs. Alpha helices, sheets, and turns are referred to as _ of proteins. The overall structure of a protein is referred to as _.Fill in the Blank Questions The amino acid that contains a weakly acidic “phenolic” group is _. _ is a fibrous protein and is the primary component of wool and hair. Every third residue in the protein collagen is _. Disulfide bonds in proteins can be reduced to free sulfhydryl groups by reagents such as _. A protein is considered to be _ when it is converted into a randomly coiled structure without its normal activity. _ is the major fibrous protein present in skin, bone, tendon, cartilage, and teeth. Collagen contains _, a modified amino acid. Agents such as _ and guanidine hydrochloride denature proteins by disrupting the noncovalent interactions. _ refers to the spatial arrangement of subunits and the nature of their interactions The _ -sheet structure occurs when the two strands are oriented in opposite directions (N C).Multiple Choice Questions What determines a proteins function? A) structure B) gene sequence C) N-terminal amino acids D) None of the above.E) All of the above. Key properties of proteins include A) a wide range of functional groups. B) an ability to possess either rigid or flexible structures as dictated by functional requirements. C) the ability to interact with other proteins. D) a and b. E) All of the above. What charged group(s) are present in glycine at a pH of 7? A) NH3+ B) COO- C) NH2+ D) a and b E) a, b, and c At a pH of 12, what charged group(s) are present in glycine? A) -NH3+ B) -COO- C) -NH2+ D) a and b E) a, b, and c In what pH range is zwitterionic Alanine the predominate structure?A) 02 B) 914 C) 810 D) 24 E) 29 Which amino acids contain reactive aliphatic hydroxyl groups? A) serine and methionine B) serine and threonine C) methionine and threonineD) cysteine and methionine E) cysteine and threonine Positively charged amino acids at a neutral pH are_. A) lys, arg, and his B) his, arg, and cys C) cys, arg, and metD) lys, arg, and pro E) arg, glu, and his _ is the N-terminus of the peptide Phe-Ala-Gly-Arg.A) Ala B) Phe C) Phe and Arg D) Arg E) None of the above. What is the approximate mass of a protein containing 200 amino acids? (Assume there are no other protein modifications.) A) 20,000 B) 11,000 C) 22,000 D) 222,000 E) None of the above. _ won a Nobel Prize for his landmark work in sequencing the protein insulin. A) Pauling B) McClintock C) Gilbert D) Maxam E) Sanger Why is the peptide bond planar? A) Bulky side chains prevent free rotation around the bond. B) It contains partial double-bond character, preventing rotation. C) Hydrogen bonding between the NH and C=O groups limits movement. D) None of the above. E) All of the above. The configuration of most -carbon atoms of amino acids linked in a peptide bond is A) cis. B) circular. C) parallel. D) trans. E) perpendicular. What structure(s) did Pauling and Corey predict in 1951? A) helix B) sheet C) turns D) a, b, and c E) a and b Which of the following protein(s) contain examples of helical character? A) keratin B) ferritin C) myosin D) tropomyosin E) All of the above. Where are and turns and loops often found? A) in a hydrophobic pocket B) on the interior cleftC) at the protein interface with ligand D) on the surface of proteins E) None of the above. What are some of the modifications that proteins acquire? A) cleavage and trimming of the protein B) addition of carbohydrate groupsC) phosphorylation of certain groupsD) a, b, and c E) b and c Which of the following amino acid residues would most likely be buried in the interior of a water soluble, globular protein? A) Asp B) Ser C) Phe D) Lys E) GlnShort-Answer Questions How does a proteins amino acid sequence influence the tertiary structure? What is the advantage of having 20 different amino acids available to form proteins? What is the advantage of protein interaction and assembly with other proteins? What are the three aromatic amino acids? Which amino acid side chains are capable of ionization? How does the protein backbone add to structural stability? Why are all the theoretical combinations of phi and psi not possible? Describe some of the features of an helix. What is the “hydrophobic effect” as it relates to protein structure? What is a protein domain? What are prions? In the ribonuclease experiments performed by Anfinson, what was the significance of the presence of the reducing agent mercaptoethanol? What is the advantage of having certain regions of partially correct folded regions? Matching QuestionsUse the following to answer questions 1-10:Choose the correct answer from the list below. Not all of the answers will be used.a) HPLCb) specific activityc) MALDI-TOF mass spectrumd) zonal centrifugatione) nascentf) SDSg) epitopeh) Svedbergi) immunoglobulinj) centrifugationk) overlap peptidesl) affinity chromatography The ratio of enzyme activity relative to total protein is called _. The first step in protein purification from a homogenate is usually _. _ is a type of purification based on the attraction of the protein for a particular chemical group. _ should be added prior to gel electrophoresis to denature the proteins. Sedimentation coefficients are described as _ units. Proteins with different sedimentation coefficients can be separated by _. In order to sequence a whole protein, _ are used. _ proteins are used to describe the original, uncleaved protein. _ is another name for an antibody. _ is another name for an antigenic determinant. Fill in the Blank Questions Proteins can be separated from small molecules and ions through a semi-permeable membrane by _. Exclusion gel or gel-filtration chromatography separates molecules on the basis of _. _ is a chemical reagent that is often used to detect the presence of amino acids. In the Edman procedure for peptide sequence, phenyl isothiocyanate is used to selectively remove the _ residue as a PTH-derivative. Disulfide bonds in peptides and proteins are readily oxidized to cysteic acid residues by treatment with _. MALDI-TOF is the abbreviation for _. Automated peptide synthesis involves the activation of the carboxyl group of the incoming amino acid by _ and then reaction with the amino group of the growing peptide chain. Polypeptides can be fragmented into smaller peptides by cleavage with chymotrypsin, which hydrolyzes the peptide bond at the C-terminal side of _ residues. _ gels are often used as the media for electrophoretic techniques such as SDS-PAGE and isoelectric focusing. The mobility of proteins in SDS-PAGE is inversely proportional to the _.Multiple Choice Questions When enzymes are purified, the assay is often based on A) light absorbance. B) temperature changes. C) catalytic activity. D) mRNA levels. E) pH. Proteins that are not catalysts are often assayed using A) antibody binding assays. B) None of the above. C) catalytic activity. D) All of the above. E) amino acid analysis. What is the advantage of adding SDS to gel electrophoresis? A) SDS colors the proteins for visualization. B) SDS reduces disulfide bonds. C) SDS allows proteins to be separated on the basis of approximate mass. D) None of the above. E) All of the above. Two-dimensional electrophoresis is a combination of what two techniques? A) isoelectric focusing and affinity chromatography B) ion-exchange chromatography and SDS-PAGE C) affinity chromatography and SDS-PAGE D) isoelectric focusing and SDS-PAGE E) isoelectric focusing and ion-exchange chromatography Which of the following affect the sedimentation of a particle? A) mass B) shape C) the density of the solution D) All of the above.E) a and b Cyanogen bromide cleaves the peptide bond at A) the carboxyl side of Arg and Lys residues. B) the carboxyl side of Met residues. C) the amino terminus. D) None of the above. E) All of the above. Trypsin cleaves the peptide bond at A) the carboxyl side of Arg and Lys residues. B) the carboxyl side of Met residues. C) the amino terminus. D) None of the above. E) All of the above. Which of the following techniques can be used to determine the site of a disulfide bond? A) Edman degradation B) MALDI-TOF C) affinity chromatography D) SDS-PAGE E) diagonal elect