课程名称︰生物化学 课程性质︰化学系五选三必修 课程教师︰陈平 开课学院：理学院 开课系所︰化学系 考试日期（年月日）︰2012/04/25 考试时限（分钟）：90mins 是否需发放奖励金：是 （如未明确表示，则不予发放） Name(1pt)_____ 学号(1pt)_____ (Total 120 pts, maximum 105 pts) 1. Multiple Choice. There is only one corrcct answer for each question. (25x2 pts, 50 pts) ___1. Plasmids used in recombinant DNA technology typically A) possess a gene for antibiotic resistance. B) replicate independently of the host genome. C) are circular double stranded molecules. D) A and B. E) all of the above. ___2. Which of the following does NOT apply to the construction or use of a DNA library? A) Many segments of DNA from a cellular genome are cloned. B) cDNA libraries can be made by cloning DNA copies of mRNAs. C) The DNA copies of mRNA found in a cDNA library are made by reverse transcnptase. D) Each plasmid must contain vir genes. E) Determining the location of a particular DNA sequence in a DNA library requfres a suitable hybridization probe. ___ 3. Protein sequence comparisons can provide estimates of A) protein structure. B) protein function. C) pathways of molecular evolutionary descent. D) A and B. E) all of the above. ___ 4. Paralogs differ in A) detailed biochemical functions. B) ancestral evolution. C) ornithology. D) all of the above. E) none of the above. ___ 5. In order to determine if alignment scores are significant, sequences are compared to sequences that undergo A) inversions. B) inverse alignments. C) repeated shuffling. D) all of the above. E) none of the above. ___6.Based on their three-dimensional structures, actin and Hsp7O are considered A) heterlogs B) orthoIogS. C) paralogS. D) all of the above. E) none of the above. ___7. An example of proteins that evolved similar mechanisms by convergent evolution. A) myoglobin and hemoglobin B) chymotrypsin and subtilisin C) Hsp7O and actin D) A and B E) none of the above ___8.A selection tool used in expemental molecular evolution. A) NMR B) PCR C) affinity chromatography D) all of the above E) none of the above ___ 9. If a Cys-Cys disulfide bond is required in a structure, this wouid be an appropriate amino acid substitution for Cys. A) Arg B) Ser C) Gly D) all of the above E) none of the above ___10. Sequence identity levels for three proteins (A,B,andC) are provided low. Given all of the data, which of the following is(are) true? A B C A 100% 65% 15% B 65% 100% 50% C 15% 50% 100% A) A and B are homologous B) B and C are homologous C) A and C are homologous D) selection A and selection B E) all of the above ___11. The two proteins are 5% identical based on sequence alignment, however are very similar (virtually identical). A) the two proteins are related evolutionarily through convergent evolution B) the two proteins are related evolutionarily through divergent evolution C) the two proteins have the same function, D) A and C E) B and C ___ 12. Example of cofactor include A) Fe2+, Mg2+, and Ni2+. B) biotin and thiamine pyrophosphate. C) pyridoxal phosphate and coenzyme A. D) B and C. E) A, B, and C. ___13. One of the enzymes involved in glycolysis, aldolase, requires Zn2+ for catalysis. Under conditions of zinc deficiency, when the enzyme lacks zinc, the enzyme would be referred to as the: A) holoenzyme. B) prosthetic group. C) apoenzyme. D) coenzyine. E) substrate. ___14. An example of energy forms transformed by enzymes includes A) ion gradients. B) chemical bond energy. C) mechanical energy. D) B and C. E) A,B,and C. ___ 15. The role of au enzyme in an enzyme-catalyzed reaction is to: A) ensure that the product is more stable than the substrate. B) make the free-energy change for the reaction more favorable. C) increase the rate at which substrate is converted into product. D) ensure that all the substrate is converted to product. E) none of the above. ___16. The concept of "induced fit" refers to the fact that: A) when a substrate binds to an enzyme, the enzyme induces a loss of water (desolvation) from the substrate B) substrate binding may induce a conformational change in the enzyme, which the brings catalytic groups into proper orientation. C) enzyme-substrate binding induces an increase in the reaction entropy, thereby catalyzing the reaction. D) enzyme specificity is induced by enzyme-substrate binding. E) enzyme-substrate binding induces movement along the reaction coordinate to the transition state, ___17. The benefit of measuring the initial rate of a reaction, V0, is that at the beginning of a reaction: A) changes in [S] are negligible, so [S] can be treated as a constant. B) [ES] can be measured accurately. C) V0=Vmax, D) changes in K_M are negligible, so K_M can be treated as a constant. E) varying [S] has no effect on V0. ___ 18. Given are five K_M values for the binding of different substrates to a particular enzyme. Which has the strongest affinity? A) 150mM B) 0.15mM C) 150uM D) 1.5nM E) 15000 pM ___19. The steady state assumption, as applied to enzyme kinetics implies A) K_M=K_ES. B) the maximum velocity occurs when the enzyme is saturated C) the ES complex is formed and broken down at equivalent rates. D) the K_M is equivalent to the cellular substrate concentration. E) the enzyme is regulated. ___ 20. Which of the following is true under the following conditions: The total enzyme concentration is 5nM. the substrate concentration is 5 mM. and the K_M is 5uM. A) the enzyme is saturated with substrate. B) most of the enzyme does not have substrate bound, C) there is more enzyme than substrate. D) all of the above. E) none of the above. ___21. To calculate the turnover number (k_cat,k2 ) of enzyme need to know: A) the initial velocity of the catalyzed reaction at low [S]. B) initial velocity of the catalyzed reaction at [S] >> K_M. C) the total enzyme D) A and C E) B and C. ___22. For the three enzymes A,B,and C (right). A) A has a lower Vmax than B. B) B has the same Vmax as C C) A has a higher K_M than C D) selection B and selection C E) all of the above ___23 The following data were obtained in a study of an enzyme known to follow Michaelis-Menten kinetics V0(umol/min) Substrate added(mmol/L) 217 0.8 325 2 433 4 488 6 647 1000 The K_M for this enzyme is approximately A) 1 mM. B) 2 mM. C) 4 mM. D) 6 mM. F) 1,000 mM. ___24. Multiple substrate enzyme reactions are divided into different classes A) sequential displacement and double displacement. B) double displacement and concerted displacement. C) sequential displacement and ping-pong. D) A and C. E) B and C. ___25. In this type of inibition the enzyme can form a complex with either the substrate (ES) or the inhibitor (EI), but not both. A) competitive B) non-competitive C) uncompetitive D) mixed E) all of the above II.Fill in the blanks(25*2 pts, 50 pts) 1.Name the four main types of mutations a)__ b)__ c)__ d)__ 2.The "i" in RNAi stands for ____ 3.Rank the following three types of information from high to low in conservation A:amino acid sequence B:nucleic acid sequence C:3D structure 4.Name the six classes of enzyme a)__ b)__ c)__ d)__ e)__ f)__ 5.A 10 fold change in equilibrium constant is worth how many kcal/mol at 25℃ 6.Please rank the following forces from strongest to weakest A.covelent bond B.electrostatic interactions C,hydrogen bonding D.van der Waal's interaction 7.For the following curves obtained using different concentrations of the same enzyme (below). The curve with the highest enzyme concentration is__ V0 ↑ ______ D ︱╱______ C ︱╱______ B ︱╱______ A ︱╱ ──────→ [S] 8.For the curves obtained using the same concentrations of the given enzyme (below). The curve with the highest substrate concentration is__ [P] ↑ ______ D ︱╱______ C ︱╱______ B ︱╱______ A ︱╱ ──────→ Time 9.Considering inhibitors A and B of the same enzyme:(A1 and A2 have different concentrations of A)__(A,B) is a competitive inhibitor. There is more inhibitor in curve__(A1,A2) 10.An enzyme was assayed in the presence of two different inhibitors in different experiments, The Lineweaver-Burk plots are shown below. Inhibitor__(A,B) is a non-competitive inhibitor 11.List the three types of irreversible inhibitor form high to low in selectivity a)__ b)__ c)__ 12.Which dipeptide does penicillin mimic? 13.Write the generic mechanism for enzyme catalysis that gives Michaelis-Menten behavior E+S 14.Please write the Michaelis-Menten equation V0= III.Amino acid structure:Draw the chemical structure, including stereochemistry, the indicated amino acid and the most likely substituting amino acid (6*3 pts 18pts) 1.Thr 2.Arg 3.Trp answers I.EDEAC CBCEE BECEC BADCA EBBDA II. 1.deletion, substitution, insertion, designed genes 2.interference 3.C>A>B 4.oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases 5.1.36 6.A>B>C>D 7.D 8.D 9.B, A1 10.B 11.suicide inhibitor, affinity label, group specific reagent 12.DAla-DAla 13. k1 k2 E+S←→ ES → E+P k-1 14.V0=Vmax[S]/([S]+k_M) III. 1.serine 2.lysine 3.tyrosine --

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