生物化学复习题.docx

生物化学复习题.docx

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生物化学复习题

第二章复习题

1）judgement:

Asforaminoacids,thenonionicformdoesnotoccurinsignificantamountsinaqueoussolution.ThezwitterionpredominateatneutralpH.Answer:

correct

2）judgement:

ProteinsareassembledfromD-aminoacids

answer:

false,ProteinsareassembledfromL-aminoacids

3）WHICHAMINOACIDSHASN’TACHIRALA-CARBONATOM？

A．LYSINEB.ALANINEC.SERINED.GLYCINE

4）whichoneofthefollowingbondsisleastlikelytobreakduringproteindenaturation?

a.Hydrophobicb.Hydrogenc.Disulfidee.Electrostatic

5）inbiologicalmembranesthepredominantinteractionbetweentheintegralproteinsandphospholipidsisprobably

A.Hbond.B.Hydrophobicinteraction.C.Ionicinteraction.D.covalentlinkage.

6）whichofthefollowingmutationswouldyouexpecttocausethemostdrasticalterationinthefunctionalperformanceofapolypeptidechain?

（assumingthereplacementisn’tattheactivesite）

A.Replacementofglutamatewithlysine.B.Replacementofvalinewithalanine.

C.Replacementofasparticacidwithglutamicacid.D.Replacementoflysinewitharginine.E.Replacementoftyrosinewithphenylalanine.

7）Inducedfit

A.isaconformationalchangebroughtaboutbythebindingofsubstratetoanallostericsite.

B.isalsoknownascooperativebindingandrequiresenzymeswithmorethanonesubunit.

C.isaconformationalchangeevokedbybindingofsubstratetotheactivesiteofanenzyme.

8）thepeptidebondhasallofthefollowingcharacteristicsexcept

A.planarity.B.freedomtorotate.C.polarity.D.greaterstabilityintransconfiguration.E.partialdoublebondcharacter.

9）Intheregulationofanoverallmetabolicsequence,whichofthefollowingreactionsismostlikelytobemodulatedbyallostericeffectors?

A.Anyreactionofthesequence.B.Thelastreactionofthesequence.

C.Theinitialreactionofthesequence.D.Thefastestreactionofthesequence.

E.Theslowestreactionofthesequence.

10）Ligasesareenzymesthatcatalyzewhichofthefollowingtypeofreaction

A.formationofbondswithATPcleavage.B.additiontodoublebonds.

C.hydrolysisreactions.D.transferoffunctionalgroups.E.oxidation-reductionreactions.

11）Inthecaseofanenzymedisplayingasigmoidrelationshipbetween　velocityandsubstrateconcentration,itcanbeconcludedthat

A.thebindingofonesubstratemoleculehindersthebinding　ofothers.

B.theenzymecontainsonlyonebindingsiteforsubstrate.

C.substratebindsmoreeasilyatlowconcentrationsthanat　highconcentrations.

D.theenzymemustcontainatleastfoursubunits.

E.theenzymedisplayscooperativityintermsofsubstrate　binding.

12）.threeproteins,a,bandc,withisoelectricpointsof8.8,6.8and4.7respectively,areappliedtothetopofadiethylaminoethylcellulosecolumn（anionexchanger）equilibratedwithabufferofph8.0.thesamebufferispassedthroughthecolumnandthesodiumchlorideconcentrationisprogressivelyincreased.thethreeproteinswillappearinthecolumneffluentintheorderof

A.A,B,C.B.B,C,A.C.C,B,A.D.A,C,B.

13）.Drawageneralaminoacidandidentifythetwofunctionalgroupscommontoall.（作图题）

aminogroup,carboxylgroup

14）Drawthereactionthatjoinstwoaminoacidstoformapeptidebond.（作图题）

15）Thestructureoftheaminoacidisoleucineis:

（a）Howmanychiralcentersdoesithave?

2

（b）Howmanyopticalisomers?

4

（c）Drawperspectiveformulasforalltheopticalisomersofisoleucine.

16）accordingtothefollowinginformation,tellmethepIvalueofalaine,lysineandglutamicacid.（计算题）

PIofalanineequaltotheaverageof2.34and9.69,or6.02

PIofglutamicacidequaltotheaverageof2.19and4.25,or3.22

PIoflysine,PIequaltotheaverageof8.95and10.79,or9.87

17）judgement：

Amixtureofaminoacidscanbeseparatedonthebasisofpolarity.ifthesolidphasearepolarmaterials，Themostpolaraminoacidgofast.

False，Amixtureofaminoacidscanbeseparatedonthebasisofpolarity.ifthesolidphasearepolarmaterials，Themostpolaraminoacidgoslow,andtheleastaminoacidgofast.

18）Histidinehasthreeionizablefunctionalgroups.Drawthestructureofhistidineineachionizationstate.WhatisthenetchargeofhistidineatpH1,4,8,and12?

ForeachpH,willhistidinemigratetowardtheanode（+）orcathode（-）whenplacedinanelectricfield?

（综合题）

19）Ifthesamplecontain0.4gofNitrogen,tellmetheamountofproteinthatthesamplewillcontain.（计算题）

Answer:

Proteincontain16%Nitrogen.1gN=6.25gprotein,thesamplewillcontain_2.5_gprotein.（0.4X6.25=2.5）

20）judgement：

GlobularProteinsisUsuallywatersoluble,compact,roughlysphericalwithHydrophobicinterior,hydrophilicsurface.Correct

21）majorcomponentsofhairandnailsare：

A.Α-keratinsb.Collagenc.Globularproteins

22）apeptidecontainingmorethanadozenaminoacidsis：

a.dipeptideb.polypeptidec.multimers

23）TheIsoelectricPointofPepsinPepsinofgastricjuice（pH≈1.5）hasapIofabout1.WhatfunctionalgroupsmustbepresentinrelativelylargenumberstogivepepsinsuchalowpI?

Whataminoacidscancontributesuchgroups?

Answer：

Carboxylgroup,Aspartate,Glutamine

24）ThepIofhistoneisveryhigh,about10.8.Whataminoacidsmustbepresentinrelativelylargenumbersinhistone?

InwhatwaydotheseresiduescontributetothestrongbindingofhistonetoDNA?

Answer:

Lysine,Arginine,HistidineElectrostaticattraction

25）onecancalculatetheapproximatenumberofaminoacidresiduesinasimpleproteincontainingnootherchemicalgroupbydividingitsmolecularweightby-_____.

A.138b.128c.110

26）Whatistheapproximatemolecularweightofaproteincontaining682aminoacidsinasinglepolypeptidechain?

682*110=75020

27）proteincontainonlyaminoacidandnootherchemicalgroupiscalled:

a.simpleproteinb.conjugatedproteinplexprotein

28）TheelectrophoreticmobilityofastandardproteinonanSDSpolyacrylamidegelisrelatedtoitsmolecularweight.comparedwiththepositionstowhichproteinsofknownmolecularweightmigrateinthegel,Estimatingthemwoftheunknownprotein.（log10158489=5.2;log106309.6=3.8;log1046418=4.67）（计算题）

Theslopeofthestandardlineis（y2-y1）/（x2-x1）

（5.2-3.8）/（0.08-0.92）=1.4/（-0.84）=-1.6667

Theslopeforunknowny/（0.4-0.92）=y/（-0.52）=-1.6667

Therefore,y=0.866684andthelogofthemolecularweightis3.8+0.866684=4.666684

Themolecularweightistheantilogof4.666684=46418

29）canactwithhighspecificityopeningpeptidebondsonthecarbonylsideofphenylalanine,tryptophanandtyrosine

a.chymotrypsinb.trypsinc.pepsin

30）ASOLUTIONCONTAINEDPROTEINAWITHAPIOF6ANDPROTEINBWHOSEPIWAS9.ATWHICHOFTHEFOLLOWINGPHVALUESWOULDBOTHPROTEINSMIGRATETOTHEANODE（POSITIVE（＋）ELECTRODE）?

A.PH4B.PH6C.PH7D.PH9E.PH10

31）APARTICULARAMINOGROUPHASAPKAOF7.5.WHATISTHERATIOOFTHECONCENTRATIONSOFCHARGEDTOUNCHARGEDSPECIESINASOLUTIONATPH6.5?

A.100:

1B.10:

1C.1:

1D.1:

10

32）WHICHOFTHEFOLLOWINGPROPERTIESDOESNOTPERTAINTOPEPTIDEBONDS?

A.THEBONDCANBEHYDROLYZEDBYPROTEASESB.THEBONDCANBEHYDROLYZEDBYSTRONGACIDSATHIGHTEMPERATURESC.THEPEPTIDEBONDISPLANARD.ROTATIONABOUTTHEPEPTIDEBONDISALLOWEDE.THEPEPTIDEBONDDEMONSTRATESELECTRONRESONANCE

33）AllofthefollowingstatementsaboutserumlacticaciddehydrogenasearetrueEXCEPT:

（糖酵解一章内容）

A.itexistsasfivedifferentisoenzymes.B.itconsistsofidenticalsubunits.

C.differentformsoflacticaciddehydrogenaseattackthesamesubstratesbutwithdifferentkineticparametersD.itgivesmultiplebandsuponelectrophoresis.

34）GLUCOSE-6-PHOSPHATEDEHYDROGENASEHASANALTEREDELECTROPHORETICMOBILITYATPH8.6CAUSEDBYTHEMUTATIONOFAVALTOWHICHOFTHEFOLLOWINGAMINOACIDS?

　（1.理解）

A.ASNB.GLUC.ILED.METE.SER

1.　Whichofthefollowingaremetabolicproductsofpyruvateinhigherorganisms?

A.  Glycerol　　　B. Lacticacid　C. Acetone　　D.Acetyl-CoA　E. Ethanol

2.Acetyl-CoA

Aincludesathioesterlinkageaspartofitsstructure.

B,takespartintworeactionsofthecitricacidcycle.

C.canbeproducedonlybybreakdownofsugars.

D.doesnotplayaroleinanymetabolicpathwayotherthanthecitricacidcycle.（answer:

A.Correct!

Thethioesterbondiseasilyhydrolyzed,andthisstructuralfeatureaccountsforthereactivityofacetyl-CoA

B.No.Acetyl-CoAtakespartonlyinthefirstreaction,theonethatproducescitrate.

C.No.Acetyl-CoAisalsoaproductoffattyacidbreakdown（aswellasthebreakdownofsomeaminoacids）

No.Acetyl-CoAisakeyintermediateinanumberofmetabolicpathways.）

3.Regenerationofoxaloacetatefromsuccinyl-CoA

a.doesn’trequireoxidizingagent.b.includeahydrationreaction.c.requireanoxidationfollowedbyreductionofcycleintermediate.d.requireATP.

4.The6-carboncompoundcitricacid

a.isformedbycondensationoftwothree-carbonpyruvatemolecules.

b.isformedfromthereactionofa2carbonacetylgroupandoxaloacetate,whichhas4carbons.

c.iscleavedtoa2-carbonanda4-carboncompound.

d.iscleavedtotwo3-carbonpyruvate.

5.Theconversionofisocitratetoalpha-ketoglutarate,

a.isanoxidativedecarboxylation.b.requirethiaminepyrophosphate（TPP）.

c.requirescoenzymeA.d.isthelaststepinthecitricacidcycle.

6.Theconversionofsuccinatetofumarateisuniqueamongthecitricacidcyclereactionsinthatit：

requirelipoicacid（硫辛酸）;involvecleavageofadoublebond;isadehydrationreaction;iscatalyzedbyamembrane-boundenzyme.

7.Thecitricacidcycleasawhole：

a.producesacetyl-CoA.b.consumeGT