LS3 Johnson W13 MT2 Form A

7/28/2019 LS3 Johnson W13 MT2 Form A

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LS3 MIDTERM II EXAM

INSTR: L. JOHNSON March 1, 2013

NAME:_________________________________(last) (first)

I.D. #__________________________________

TA ___________________________________

Test Form A

INSTRUCTIONS

This exam is 10 pages long. Before starting make sure you have all the pages.

Using a number 2 pencil, on the front of your scantron fill in the Instructor (Johnson), Class(LS3), Hour (12:00 or 1:00),

Write and Bubble in your UID, your last name and first name.

On the back of your scantron Write and Bubble in your UID and Test Form (see above).


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1. Whatconceptbelowbestexplainshow40tRNAscanread61codons?a. Wobble-pairingb. Degeneratecodec. tRNAsynthetaseschargeallthetRNAsforoneaminoacidd. Alloftheabove.

2. AssumethereisonlyonetRNAforcysteine.Usingthegeneticcodeandwobblerulesonthelastpageoftheexam,whichanticodonbelowwouldyouexpecttofindonthecysteinetRNA?(makesureitdoesntrecognizeanynon-

cysteinecodons)

a. 5GCA3b. 5ACG3c. 5ICA3d. 5ACI3

3. Intheimageabove,thegeneisbeingtranscribed

a. fromrighttoleftb. fromlefttorightc. Thereisnotsufficientinformationtodeterminethedirectionof

transcription.

4. Whichofthefollowingistrueofprokaryotictranslationinitiation?a. ThesmallribosomalsubunitscansthemRNAforthefirstAUG.b. ThesmallribosomalsubunitscansthemRNAforaTATAsequence.c. ThesmallribosomalsubunitbindsIF1intheAsiteandIF3intheE

site.d. Thesmallribosomalsubunitcontainsthe23SrRNA.e. Alloftheabove.

5. WhichofthefollowingproteinscanbindtotheAsiteoftheribosome?a. RF1b. RF2c. RRFd. Alloftheabove.

6. Whichofthefollowingmoleculesisnotanallostericeffector?a. IPTGb. X-GALc. arabinosed. tryptophane. cAMP


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7. Theelongationsfactors,EF-TuandEF-Ga. arebothGpoteins.b. bothplayaroleisescortingchargedtRNAstotheAsite.c. bothundergoaconformationchangeuponhydrolysisofGTP.d. aandbe. aandc8. Duringtranslation,peptidebondformationinvolvesanucleophilicattack.

Whichatomactsasthenucleophile?

a. Theoxygenfromthecarboxylterminusofthegrowingpeptidechain.b. Theoxygenfromthecarboxylterminusoftheincomingamino-acyl

tRNA.

c. Thenitrogenfromtheaminoterminusofthegrowingpeptidechain.d. Thenitrogenfromtheaminoterminusoftheincomingamino-acyl

tRNA.

9. Whichofthefollowingistrueofeukaryotictranslationinitiation?a. The5caponthemRNAisrecognizedbyaninitiationfactor.b. TheinitiatingtRNAischargedwithmethionineandthenmodifiedbyformylation.c. TheShine-Dalgarnosequencebasepairstothe16SrRNA.d. IF1bindsandblockstheAsite.e. Alloftheabovearetrue.

10.Whichofthefollowingfactorsplayaroleintwostagesoftranslation(initiation,elongation,termination)?

a. EF-Tub. EF-Gc. IF3d. aandbe. bandc

11.WhichofthefollowingDNAbindingmotifsgraspDNAlikeapairofscissors?a. Helix-turn-helixb. Znfingerc. Homeodomaind. Basicleucinezippere. Alloftheabove.

12.Riboswitchesa. haveanaptamerandexpressionplatformb. bindsmallmetabolitesandaltertheRNAsecondarystructurec. mayregulateeitherattenuationortranslationinitiation.d. Alloftheabove.

13.Whichofthefollowingproteinsisunderpositiveallostericcontrol:a. IF1b. Gal80pc. CAPd. Lacrepressore. Sigmafactor


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14.Whichofthefollowingconclusionsareconsistentwiththedatashownabove.

a. -galactosidaseislessstablethanitsmRNA.b. Additionoftheinducerslowsthegrowthrateofthecell.c. Eliminationoftheinducerhasadrasticeffectonthelevelsof-

galactosidase.d. AdditionoftheinducerleadstoanincreaseinmRNAfollowedbyan

increaseinprotein.

15.ChargingoftRNAsbyaminoacylsynthetasesisatwostepprocess.Thefirststepcanbedescribedas:

a. Transesterificationb. Phospho-transferreactionc. Adenylylationd. Hydrolysis

16.InthesecondstepinthetRNAchargingreaction,thenucleophileisa. The2OHonATPb. Thecarboxyloxygenontheaminoacidc. The3OHonthetRNAd. Thenitrogenontheaminoacid

17.Attenuationinthetrpoperondependsonconcurrenttranscriptionandtranslation.Whatwouldyoupredictwouldoccurifproteinsynthesiswas

blockedbypuromycininmediacontaininglowtryptophanlevels?

a. Withouttranslation,nosecondarystructurewouldforminthemRNAandsothetrpoperonwouldbetranscribed.

b. Withouttranslation,region1wouldpairwithregion2,region3wouldpairwithregion4andtranscriptionwouldbeattenuated.

c. Withouttranslation,region2wouldpairwithregion3andtranscriptionwouldnotbeterminated.

d. Lowtryptophanwouldleadtoderepressionandthetrpoperonwouldbetranscribedevenwithouttranslation.

18.PolIItranscriptsaremodifiedatthe5endwitha. ATPina5-3linkageb. ATPina5-5linkagec. GTPina5-3linkaged. GTPina5-5linkage


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19.PolIItranscriptsaremodifiedatthe3enda. bycleavagefollowedbyadditionofpoly-Ab. byterminationfollowedbyadditionofpoly-Ac. toprotectthemfromdegradationd. aandce. bandc20.WhichofthefollowingfactorsrecognizestheTATAbox?a. TFIIAb. TFIIBc. TFIIDd. THIIEe. TFIIH

21.Whichofthefollowingfactorshashelicaseactivity?a. TFIIAb. TFIIBc. TFIIDd. THIIEe. TFIIH

22.WhichofthefollowingfactorsphosphorylatesthePolIICTDduringinitiation?

a. TFIIAb. TFIIBc. TFIIDd. THIIEe. TFIIH

23.PhosphorylationofthePolIICTDa. recruitspolyadenylationenzymes.b. recruitscappingenzymesc. promotesescapefromthepromoterd. recruitssplicingenzymese. Alloftheabove.

24.WhenE.coliisgrowninmediacontainingbothglucoseandlactosea. thelacoperonisinducedbuttranscriptionisnotactivated.b. thelacoperonisactivatedbutnotinduced.c. theleveloftranscriptionfromthelacoperonisconsideredbasal.d. aandce. bandc

25.TheTorpedoModelreferstoa. howDNAissynthesizedatthereplicationfork.b. howRNAisterminatedineukaryotesc. howRNAisterminatedinprokaryotesd. howtranslationisterminated


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26.Inthegraphabove,thepeaksofradioactivitylookdifferentfromthepeaksof

OD260because

a. theradioactivityisonlymeasuringmRNAandtheOD260isonlymeasuringrRNA.

b. theradioactivityisonlymeasuringnewlysynthesizedRNAandtheOD260ismeasuringtotalRNA,whichismostlyrRNA.

c. theradioactivityismeasuringRNAandtheOD260ismeasuringprotein.

d. Alloftheabove.27.WhichofthefollowingisNOTtrueaboutyeastmatingtypecontrol?

a. Mcm1incombinationwith1activatesspecificgenes.b. Haploidspecificgenesareonunlessrepressedinadiploidcell.c. Mcm1incombinationwitha1activatesaspecificgenes.d. a1and2combinetoformarepressor.

28.Theexpressionofeveinstripe2oftheDrosophilaembryoisa. activatedbybicoidandhunchbackb. activatedbygiantandbicoidc. repressedbykruppelandhunchbackd. repressedbybicoidandkruppel.

29.Generaltranscriptionfactorsineukaryotesa. bindtoenhancerstoregulatetranscriptioninatissuespecificmannerb. areresponsibleforrecognizingtheTATAboxc. areneededatallpromotersduringtranscriptioninitiationd. bandce. Alloftheabove

30.Thefirsttransesterificationreactionthattakesplaceduringsplicinga. iscatalyzedbysnRNPsb. involvesthebranchpoint2OHattackingthe3splicesitec. occursafteractivationofthesnRNPbyadenylylationd. aandbe. Alloftheabove


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31.WhichofthefollowingisNOTtrueofsplicing?a. U2snRNPbindstothebranchpointb. U1snRNPbindstothe3splicesitec. Theformationofthespliceosomebringsthe5and3splicesitesnear

eachother

d. Alariatisformedintheintron.32.Alternativesplicinga. allowsexonstobesplicedtogetherinreverseorder.b. allowsexonstobesplicedtogetherintheDNAtocreatenewgenes.c. allowsexonstobesplicedtogetherinmorethanonewaytoencode

morethanoneproteinfromasinglegene.

d. Alloftheabove.33.TheGal80prepressorinhibitstranscriptionby

a. bindingtoGal3pandblockingactivationb. bindingtoGal4pandblockingactivationc. bindingtotheGAL1operatorandblockingRNApolymerased. bindingtotheUASandblockingGal4pbinding34.Steroidhormonesa. bindtoreceptorproteinseitherinthecytoplasmornucleusb. causeacascadeofphosphorylationeventsthatactivatestranscriptionc. havereceptorsthatbindtoDNAthroughtheirhomoeodomainmotifd. needtobeactivelytransportedintothecell.

35.WhichofthefollowingisNOTtrueofthelacandaraoperons?a. Theyarebothregulatedbyactivatorsandrepressorsb. TheirrespectiverepressorshavetwoDNAbindingsitesandcancause

loopstoformintheDNA

c. Theyarebothrepressedwhenlactoseorarabinose,respectively,areabsent

d. CAP-cAMPactivatesbothoperonswhenglucoselevelsarehigh36.Laggingstrandsynthesis

a. isdiscontinuousb. occursinthesamedirectionasthereplicationforkmovementc. requirescontinualrepriming.d. aandbe. aandc

37.DNAligasecreatesaphosphodiesterbonda. betweena5OHanda3PO4inanickedDNA.b. betweena3OHanda5PO4inanickedDNA.c. usingadenylylationasthefirststepinthereaction.d. aandce. bandc


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38.DNAreplicationinbacteriadoesnotrequirewhichofthefollowingproteins?a. Ligaseb. Helicasec. Topoisomerased. TBPe. SSB39.MeselsonandStahlshowedthatDNAreplicationisa. Bidirectionalb. Semi-conservativec. Discontinuousd. 5to3e. alloftheabove

40.RNAprimersareremovedbyDNApolymeraseIusinga. 3to5exonucleaseactivityb. 5to3exonucleaseactivityc. theirproof-readingfunctiond. Alloftheabove.41.DNAhelicasesarerequiredinDNAreplicationtoa. relievethetorsionalstraincausedbysupercoiling.b. unwindtheRNA-DNAhybridsoitcanbeexcisedc. unwindtheDNAatthereplicationforkd. Alloftheabove.

42.Theobservationthattheleadingandlaggingstrandpolymerasesarefoundtogetherinalargereplicationcomplex

a. leadtotheproposaloftheTorpedoModelb. leadtotheproposaloftheTrumpetModelc. leadtotheproposaloftheTromboneModeld. leadtotheproposaloftheTornadoModel

43.Whichofthefollowingenzymescanbeclassifiedasareversetranscriptase?a. Primaseb. RNApolymerasec. Telomerased. DNApolymerase

44.Therepeatsequencesfoundattheendsofchromosomesa. aresynthesizedusingaRNAtemplatecarriedbyTelomerase.b. protectthechromosomesfromdegradationc. arelongerinyoungcellsd. aandbe. Alloftheabove.

45.Duringactivationoftranscriptionineukaryotes,co-activatorsincludea. histoneacetyltransferasesb. histonedeacetyltransferasesc. histoneremodelingproteinsd. aandce. bandc


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46.WhatwouldyoupredictwouldhappenifaeukaryoticinvitrotranslationsystemwasgivenaprokaryoticpolycistronicmRNA?

a. ItwouldtranslateeachORFpresentonthemRNA.b. ItwouldtranslateonlythefirstORFpresentonthemRNAc. Itwouldnottranslateitatallwithouta5cap.

47.WhenJacobandMonodscreenedforrepressormutantsE.coli,whatdidtheyputintheirmedia?a. glucoseb. X-GALc. IPTGd. aandbe. aandc

48.ExperimentsnotdescribedinclassshowedthatwhenaeukaryoticmRNAwashybridizedtoitsgenomicDNA,regionswereobservedthatloopedout

(werenotcomplementary).Thisresultiscartoonedbelow.

1

Inthiscartoon,whichstrandrepresentstheDNA?a. 1b. 2

49.Supposereplicationwasunidirectionalfromtheoriginofreplication.Wouldtherestillbealeadingstrandandalaggingstrand?

a. Nob. Yes50.Whichtermbelowdescribestheprocessofmovementoftheribosometothe

nextcodon?

a. translationb. translocationc. transformationd. transcription

2


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WobbleRules

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LS3 Johnson W13 MT2 Form A