清華大學本科生考試試題專用紙

1、清華大學本科生考試試題專用紙考試課程Biochemistry II2001 年 6月11 日說明：1.請選擇正確答案，填在適當?shù)臋M線處（1-30題）或?qū)懺诖痤}紙上（31-33題）;2. 答案可能是一個或多個；3. 每題的分數(shù)在標在了題目后面；4. 本卷滿分為100.1. If the AG of the reaction A * B is -A. The react ion will proceed spontan eously from left to right at the give n con diti ons.B. The react ion will proceed spontan

2、 eously from right to left at sta ndard con diti ons.C. The equilibrium constant favors the formation of B over the formation of A.D. The equilibrium constant could be calculated if the initial concentrations of A and B were known.直 oE. The value of G is also negative.Answer(s): A, D2. Which of the

3、following statements about ATP and its roles in cells are true? ( 2 points)A. The ATP molecule is kin etically un stable and is thus con sumed with in about one minute following its formation in cells.B. ATP provides free en ergy to a thermody namically un favorable react ions by group tran sfer, al

4、ways don at ing a Pi to form a covale nt in termediate.C. ATP can be regenerated by coupling with a reaction that releases more free energy than does ATP hydrolysis.D. A transmembrane proton-motive force can drive ATP synthesis.E. The active form of ATP is usually in a complex with Mg .Answer(s): C,

5、 D, E3. A common moiety for NADP, NAD, FMN, FAD, and coe nzyme A is: (2 poi nts)A. A pyrimidine ring;B. A three ring structure;C. An ADP;D. A pyranose ring;E. A triphosphate group.Answer(s): C144. If the C-1 carb on of glucose were labeled with C, which of the carb on atoms in pyruvate would be labe

6、led after glycolysis? ( 2 points)A. The carboxylate carb on;B. The carb onyl carb on;C. The methyl carb on.Answer(s): C5. Which of the followi ng are metabolic products of pyruvate in higher orga ni sms? (2 poin ts)A. GlycerolB. Lactic acidC. Acet oneD. Acetyl-CoAE. Etha nolAnswer(s): B, D6. In dica

7、te whether each of the follow ing stateme nts about the pen tose phosphate pathway is true (T) or false (F). (5 poin ts)A. It gen erates NADH for reductive bios yn theses. FB. The reacti ons occur in the cytosol. TC. Transketolase and transaldolase link this pathway to gluconeogenesis. FD. It is mor

8、e active in muscle cells than in fat-storage cells. FE. It in terc on verts trioses, tetroses, pen toses, hexoses, and heptoses. T7. Which of the follow ing stateme nts are correct? The citric acid cycle ( 2 poin ts)A. does not exist as such in plants and bacteria, because its functions are performe

9、d by the glyoxylate cycle.B. oxidizes acetyl CoA derived from fatty acid degradati on.C. produces most of the CO 2 in an aerobic orga ni sms.D. provides succi nyl CoA for the syn thesis of carbohydrates.E. provides precursors for the syn thesis of glutamic and aspartic acids. Answer(s): B, E8. Match

10、 the cofactors of the pyruvate dehydrogenase complex with their corresponding enzyme components and with their roles in the enzymatic steps that are listed. ( 5 points)A. Coe nzyme A: 3,7B. NAD +: 2, 9C. Thiamine pyrophosphate (TPP): 1,5D. FAD: 2,_6E. Lipoamide: 3, 4,8(1) . Pyruvate dehydroge nase c

11、omp onent(2) . Dihydrolipoyl dehydroge nase(3) . Dihydrolipoyl tran sacetylase(4) . Oxidizes the hydroxylethyl group(5) . Decarboxylates pyruvate(6) . Oxidizes dihydrolipoamide(7) . Accepts the acetyl group from acetyllipoamide(8) . Provides a long, flexible arm that coveys in termediates to differe

12、 nt en zyme comp onent.(9) . Oxidizes FADH2.9. Matching the role in fatty acid oxidation and/or mobilization to the appropriate component listed below. (5 poin ts)A. Bile salt: 2B. Serum albumi n:5C. ApoC-II:4D. Apolipoprotein:3E. Carn iti ne:1(1) . Acts as a“ carrier ” of fatty acids across the inn

13、er mitocho ndrial membra ne.(2) . Acts as a biological deterge nt, disrupti ng fat globules into small mixed micelles.(3) . Binds and tran sports triacylglycerols, phospholipids, and cholesterol betwee n orga ns.(4) . Activates lipoprote in lipase, which cleaves triacylglycerols into their comp onen

14、 ts.(5) . Binds some fatty acids molibized from adipocytesand tran sports them in the blood to heartand skeletal muscle.10. Which of the following answers complete the sentence correctly? Surplus dietary amino acids may be con verted into (2 poin ts)A. protei ns.B. Fats.C. ketone bodies.D. glucose.E

15、. a variety of biomolecules for which they are precursors.Answer(s): A,_B,_C,_D,E-11. Which of the follow ing compo unds serves as an acceptor for the amino groups of many amino acids during metabolism? ( 2 points)A. Glutami neB. Asparagine.C. : -ketoglutarate.D. OxaloacetateE. GlutamateAnswer(s):C1

16、2. Match the fun ctio ns for the coe nzymes that are in volved in ami no acid metabolism. (4 poin ts)A. Pyridoxal phosphate: (3)B. Coe nzyme B12： (2)C. Tetrahydrobiopterin: (1)D. NAD+:(1)E. Bioti n (4)(1) . Carries electro ns(2) . Provides free radicals(3) . Carries amino groups.Carries CO 2.13. Whi

17、ch of the followi ng experime ntal observati ons would not support the chemiosmotic model of oxidative phosphorylation? (3 points)A. If mitoch on drial membra nes are ruptured, oxidative phosphorylati on cannot occur.B. Raising the pH of the fluid in the intermembrane space results in ATP synthesis

18、in the matrix.C. Tran sfer of electro ns through the respiratory cha in results in formatio n of a proto n gradie nt across the inner mitoch on drial membra ne.D. The orientation of the enzyme complexes of the electron transfer chain results in a uni direct ional flow of H +.E. Radioactively labeled

19、 inorganic phosphate is in corporated into cytosolic ATP only in the presenee of an H gradient across the inner mitochondrial membrane.Answer(s): B14. Some photos yn thetic prokaryotes use H2S, hydroge n sulfide, in stead of water as their photosynthetic hydrogen donor. How does this change the ulti

20、mate products of photosynthesis? (2 poi nts)A. Carbohydrate (CH 2O) is not produced.B. H2O is not produced.C. Oxygen is not produced.D. ATP is not produced.E. The products do not cha nge.Answer(s): C15. Which of the follow ing are con stitue nts of chlorophylls? (2 poin ts)A. Substituted tetrapyrrol

21、e.C.D.E.F.B. Plastoq uinone.E. Phytol.F. Iron porphyri n.Answer(s): A, C, E1416. The observation that the incubation of photosynthetic algae with CO2 in the light for a very brief time (5s) led to the formation of 14C-labeled 3-phosphoglycerate suggested that the 14CO2 was condensing with some two-c

22、arb on acceptor. That acceptor was in fact which of the follow ing? (2 poi nts)A. AcetateB. Acetyl CoAC. Acetyl phosphateD. AcetaldehdydeE. Glycerol phosphateF. None of the aboveAnswer(s): F17. Which of the follow ing are com mon features of the syn theses of meval on ate (an in termediate of choles

23、terol bios yn thesis) and ket one bodies? (2 poin ts)A. Both in volve 3-hydroxyl-3-methylglutaryl CoA (HMG-CoA).B. Both require NADPH.C. Both require the HMG-CoA cleavage en zyme.D. Both occur in the mitoch on dria.E. Both occur in liver cells.Answer(s): A18. S-ade no sylmethi onine is in volved dir

24、ectly in which of the followi ng react ions. (3 poi nts)A. Methyl tran sfer to phosphatidyl etha no lam ine.B. Syn thesis of glyci ne from seri ne.C. Synthesis of polyamines.D. Conversion of homocysteine to methionine.E. Gen eratio n of the 5 cap of the eukaryotic mRNAs.Answer(s): A, C, E19. Which o

25、f the followi ng does not provide a carb on skelet on for the syn thesis of ami no acids? (2poi nts)A. succi nate.B. : -ketoglutarateC. Pyruvate.D. Oxaloacetate.E. Ribose-5-phosphate.Answer(s): A20. Which of the following compounds directly provide atoms to form the purine ring? (3 points)A. Asparta

26、te.B. Carbamoyl phosphate.C. Glutamine.D. Glycine.E. CO2.510F. NN -methylenetetrahydrofolate.G. N -formyltetrahydrofolate.H. NH4+.Answer(s): A, C, D, E, G21. Which of the following statements about ribonucleotide reductase are true? ( 2 points)A. It con verts ribonu cleoside diphosphates into 2-deox

27、yrib onu cleoside diphosphates in huma ns.B. It contains coe nzyme B 12, which gen erates free radicals n eeded for the catalysis.C. It accepts electrons directly from FADH 2.D. It receives electr ons directly from either thioredox in or glutaredox in.E. It contains two kinds of allosteric regulator

28、y sites: one for con trolli ng the overall activityand the other for con troll ing the substrate specificity.Answer(s): A, D, E22. Biosy nthetic pathways that require NADPH in clude which of the followi ng? (2 poi nts)A. Gluc on eoge nesis.B. Fatty acid bios yn thesis.C. Ketone body formati on.D. Ch

29、olesterol biosynthesis.E. Tyros ine bios yn thesis.Answer(s): B,D,E23. Homologous recomb in ati on in E. coli is likely to require which of the followi ng? (3 poin ts)A. DnaB protei n.B. RecA protei n.C. RecBCD complex.D. ATP.+E. NAD .F. Sin gle-stra nd DNA binding prote in.G. DNA-dependent RNA poly

30、merase.H. DNA polymerase I.I. DNA ligase.J. dATP.Answer(s): B, C, D, E, F, H, I, J24. Which of the following statements about E. coli promoters are correct? (2 points)A. They may exhibit differe nt tran scriptio n efficie ncies.B. For most genes they in clude varia nts of consen sus seque nces.C. Th

31、ey specify the start sites for transcription on the DNA template.D. They have identical and defining sequences.E. They are activated whe n C or G residues are substituted into their 0 regi ons by mutati on.F. Those that have sequences that correspond closely to the consensus sequences and are separa

32、ted by 17 base pairs are very efficie nt.Answer(s): A, B, C, F 25. The AAUAAA sequenee on a RNA molecule marks ( 2 points)A. The site where ribosomes bind to initiate polypeptide synthesis.B. The site where tran scripti on stops.C. The site near which the primary transcript is cleaved and a poly (A)

33、 sequence is added.D. The site where the release factor will bind to end polypeptide synthesis.E. The site where polyrib onu cleotide phosphorylase will add a stretch of ran dom seque nces.Answer(s) :_C7026. The :二 sub unit of the E. coli RNA polymerase: ( 2 poi nts)A. acts as the catalytic site for

34、 polymerizati on.B. Recog nize promoters.C. Has a proofreadi ng fun ctio n.D. In creases the processivity of the en zyme.E. Recog ni zes term in ati on sig nals.Answer(s): B27. The discontinuity of eukaryotic genes were first revealed by: ( 2 points)A. Using footpri nti ng tech niq ues.B. DNA seque

35、nce comparis on.C. RNA seque nce an alysis.D. Electr on microscopic an alysis of RNA-DNA hybrid molecules.E. Pla nt gen etic studies.Answer(s): D 28. Which of the followi ng mRNA codo ns can be recog nized by the tRNA an ticodon ICG. (2 poi nts)A.UGC.B.CGA.C.UGA.D.CGU.E.CGC.Answer(s): B, D, E29. A n

36、ew compo und, vivek ine, was recen tly discovered by a clever un dergraduate stude nt. It wasisolated from bacteria found in deep sea-dwell ing orga ni sms. Vivek ine in hibits prote in syn thesis in eukaryotes: Prote in syn thesis can in itiate, but only dipeptides are formed and these rema in boun

37、d to the ribosome. This tox in affects eukaryotic prote in syn thesis by block ing the: (2poin ts)A. bi nding of formylmethi on yl-tRNA to ribosomes.B. activity of elon gati on factors.C. activation of amino acids.D. recognition of stop signals.E. formati on of peptide bon ds.Answer(s) ：_B30. Indica

38、te whether each of the following statements about prokaryotic translation is true (T) or false (F). (7 poi nts)A. An amino acyl-tRNA syn thetase catalyzes formatio n of an ester bond. ( T )B. An mRNA molecule cannot be used to direct prote in syn thesis un til it has bee n completely tran scribed. (

39、 F )C. The positi oning of fMet-tRNA on the A site defi nes the read ing frame. ( F )D. Incoming amino acyl-tRNA are first bound to the A site. ( T )E. Formati on of the 70S in itiati on complex requires an in put of en ergy. ( T )F. The carboxyl group of the amino acid on the amino acyl-tRNA is tra

40、n sferred to the amino group of a peptidyl-tRNA.( F )G. Release factors cause the peptidyl transferase activity of the ribosome to use H2O as a substrate. ( T )31. In an attempt to determine whether a given RNA was catalytically active in the cleavage of asyn thetic oligo nu cleotide, the followi ng

41、 experime ntal results were obta in ed. When the RNA and the oligo nu cleotide were in cubated together, cleavage of the oligo nucleotide occurred. When either the RNA or the oligonucleotide was incubated alone, there was no cleavage. When the RNA was incubated with higher concentrations of the olig

42、onucleotide,saturation kinetics of theMichaelis-Me nten type were observed. Do these results dem on strate that the RNA has catalytic activity? Explain. ( 8 points)An swer:These results alone do not establish that the RNA has catalytic activity. A catalystmust be rege nerated. It is en tirely possib

43、le that the results observed could be acco un ted for by a stoichiometric, as opposed to a catalytic, in teract ion betwee n RNA and the oligo nu cleotide.In which the RNA may “ommit suicide” as the oligonucleotideis cleaved. In such anin teracti on, a porti on of the RNA would also be cleaved itself as a part of the reacti on. Four reacti on products would accumulate, two result ing from the cleavage of RNA and two from the cleavage of the oligo nu