生物化学英文版习题.docx

生物化学英文版习题.docx

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生物化学英文版习题

I.FuelMetabolism

PART1:

StructureandFunctionofProtein

Directions:

Eachofthenumbereditemsorincompletestatementsinthissectionisfollowedbyanswersorbycompletionsofthestatement.Selecttheoneletteredanswerorcompletionthatisbestineachcase.

Questions9and10

Usethestructuretoanswerquestions9and10：

Asp-Ala-Ser-Glu-Val-Arg

9.TheC-terminalaminoacidofthehexapeptideshownis

（A）alanine（B）asparagine（C）aspartate（D）arginine

10.AtphysiologicpH（7.4）,thishexapeptidewillcontainanetchargeof

（A）-2（B）-1（C）0（D）+1（E）+2

11.Whichoneofthefollowingtypesofbondsiscovalent?

（A）Hydrophobic（B）Hydrogen（C）Disulfide（D）Electrostatic

13.Whichoneofthefollowingconditionscauseshemoglobintoreleaseoxygenmore

readily?

（A）Metabolicalkalosis

（B）Increasedproductionof2,3-bisphosphoglycerate（BPG）

（C）Hyperventilation,leadingtodecreasedlevelsofCO2intheblood

（D）Replacementoftheβsubunitswithγsubunits

14.Productionofwhichofthefollowingproreinswouldbemostdirectlyaffectedin

scurvy?

（A）Myoglobin（B）Collagen（C）Insulin（D）Hemoglobin

15.Theactivesiteofanenzyme

（A）isformedonlyafteradditionofaspecificsubstrate

（B）isdirectlyinvolvedinbindingofallostericinhibitors

（C）residesinafewadjacentaminoacidresiduesintheprimarysequenceofthe

polypeptidechain

（D）bindscompetitiveinhibitors

16.AnenzymecatalyzingthereactionE+S=ES→E+Pwasmixedwith4mMsubstrate.Theinitialrateofproductformationwas25%ofVm.TheKmfortheenzymeis

（A）2mM（B）4mM（C）9mM（D）12mM（E）25mM

17.Thevelocity（v）ofanenzyme-catalyzedreaction

（A）decreasesasthesubstrateconcentrationincreases

（B）islowestwhentheenzymeissaturatedwithsubstrate

（C）isrelatedtothesubstrateconcentrationatlhVm

（D）isindependentofthepHofthesolution

Questions18and19

Refertothefollowingreactionwhenansweringquestions18and19.

Fumarate+H20↔malate

fumarase

18.Fumarasecatalyzestheconversionoffumaratetomalate.IthasaKmof5μMfor

fumarateandaVmaxof50μmol/min/mgofproteinwhenmeasuredinthedirectionofmalateformation.Theconcentrationoffumaraterequiredtogiveavelocityof25μmol/min/mgproteinis

（A）2μM（B）5μM（C）10μM（D）20μM（E）50μM

19.TheKmforfumaraseisapproximately5μMforfumarate.Thefumarateconcentrationinmitochondriaisapproximately2mM.Ifthefumarateconcentrationdroppedto1mM,thereactionratewould

（A）increaseslightly（B）decreaseslightly

（C）decreasebyonehalf（D）stayexactlythesame

20.Hexokinaseandglucokinasebothcatalyzethephosphorylationofglucosetoglucose6-phosphate.ThevaluesofKmfortheenzymesare10μMand0.02M,respectively.Ifbloodglucoseis5mMunderfastingconditionsand20mMafterahigh-carbohydratemeal

（A）hexokinasewillfunctionnearitsVmaxunderfastingconditions

（B）glucokinasewillfunctionnearitsVmaxunderfastingconditions

（C）hexokinasewillfunctionatlessthanone-halfVmaxafterahigh-carbohydratemeal

（D）glucokinasewillfunctionatlessthanone-halfVmaxafterahigh-carbohydratemeal

21.Acompetitiveinhibitorofanenzyme

（A）increasesKmbutdoesnotaffectVmax

（B）decreasesKmbutdoesnotaffectVmax

（C）increasesVmaxbutdoesnotaffectKm

（D）decreasesVmaxbutdoesnotaffectKm

（E）decreasesbothVmaxandKm

Questions22-25

Refertothegraphwhenansweringquestions22-25.

22.ThevalueofKmfortheenzymedepictedbycurveAis

（A）0.5mM（B）1mM（C）2mM（D）1μmol/min/mg（E）10μmol/min/mg

23.ThevalueofVmfortheenzymedepictedbycurveAis

（A）0.1μmol/min/mg（B）1μmol/min/mg

（C）10μmol/min/mg（D）0.5mM（E）2mM

24.CurveBdepictstheeffectofaninhibitoronthesystemdescribedbycurveA.Thisinhibitor

（A）isacompetitiveinhibitor（B）isanoncompetitiveinhibitor

（C）increasestheVmax（D）decreasestheKm

25.CurveCdepictstheeffectofadifferentinhibitorofthesystemdescribedbycurveA.Thissecondinhibitor

（A）isacompetitiveinhibitor

（B）isanoncompetitiveinhibitor

（C）increasestheVmax

（D）decreasestheKm

answer：

DBCBBDDCBBAAACAB

Directions:

Eachgroupofitemsinthissectionconsistsofletteredoptionsfollowedbyasetofnumbereditems.Foreachitem,selecttheoneletteredoptionthatismostcloselyassociatedwithit.Eachletteredoptionmaybeselectedonce,morethanonce,ornotatall.

Questions33-37

Matcheachcharacteristicbelowwiththeproteinitbestdescribes.

（A）Hemoglobin（B）Myoglobin（C）Collagen（D）Insulin

33.RequiresvitaminCforitssynthesis

34.Hasoneoxygenbindingsiteandonepolypeptidechain

35.Containsfourmoleculesofheinepermolecule