BI 213 Exam 2: Chapter 8: RNA processing

BI 213 Exam 2: Chapter 8: RNA
processing Questions and Answers
Updated 2026
ImportantBnoteBaboutBRNABprocessingB-
BAnswerAllBeukaryoticBRNAsBprocessed,BcodingBorBnotB(mRNA,BlncRNA,BsiRNA,Betc.)



àBallBRNAsBprocessedBEXCEPTBforBbacterialBRNAs



HowBisBtheB5'BendBofBaBpre-tRNABprocessed?B-
BAnswercleavageBbyBanBenzymeBcalledBRNaseBP



RNaseBPBisBaBribozyme;BanBenzymeBwhereBtheBRNABinsteadBofBproteinBisBreposibleBforBcatal
yiticBactivity



WhatBareBRNaseBPB-BAnswer·BRNaseBPBconsistsBofBRNABandBproteinBmolecules



ribozyme



involvedBinBtRNABprocessing:

catalysesBcleavageBofBtheB5'BendBofBpre-tRNA



KeyBtakeaway:

CleavageBofBpre-tRNA'sBareBcatalyzedBbyB-BAnswerribozymes



Note:Bdon'tBconfuseBRNaseBPBbyBwithBsnoRNAB-
BAnswerNoteBthatBthisBisBfundamentallyBdifferentBfromBtheBroleBofBsnoRNAsBinBsnoRNPs,BinB
whichBtheBreactionBisBcatalyzedBbyBproteinBcom-ponentsBofBtheBribonucleoproteinBcomplex.



HowBisBtheB3'BendBofBtRNA'sBgenerated?B-
BAnswerconventionalBproteinBRnaseB(ribonculeaseBenzyme)



itBaddsBaBCCABterminus

,WhyBdoBallBtRNA'sBhaveBtheBsequenceBCCABatBtheirB3'Bends?B-
BAnsweroBThisBsequenceBisBtheBsiteBofBaminoBacidBattachment,BsoBitBisBrequiredBforBtRNABf
unctionBduringBproteinBsynthesis.



KeyBnotion:BProcessingBofBtRNAsBinvolvesBadditionBofBaBCCAB3′BterminusBandBextensiveBbase
Bmodification.B-BAnswer



FigureB8.13BProcessingBofBtransferBRNAsB-BAnswerTransferBRNAsBareBderivedBfromBpre-
tRNAs,BsomeBofBwhichBcontainBseveralBindividualBtRNABmolecules.



·BCleavageBatBtheB5′BendBofBtheBtRNABisBcatalyzedBbyBtheBRNaseBPBribozyme;



·BcleavageBatBtheB3′BendBisBcatalyzedBbyBaBconventionalBproteinBRNase.



·BABCCABterminusBisBthenBaddedBtoBtheB3′BendBofBmanyBtRNAsBinBaBpost-
transcriptionalBprocessingBstep.



·BFinally,BsomeBbasesBareBmodifiedBatBcharacteristicBpositionsBinBtheBtRNABmolecule.



WhyBareBsomeBtRNABcontainBmodifiedBbases?B-BAnswer·BModificationBaltersBbase-
pairing/codingBproperties



ClevageBduringBtRNABprocessingB-BAnswer5'BendBàBRibozymeB(RNA)

3'endBàBconventionalBRNaseB(protein)



WhatBtoBknowBaboutBtRNABprocessingB-BAnswer2BProcessingBevents

1)Cleavage

2)BaseBmodification



1.Bcleavage

@B5'Bend:BRibozymeB(RNABw/BcatalyticBactivity),BcalledBRNaseBP,BcleavesBtRNA



@B3'Bend:BRibonuclease,BRNase,BcleavesBtRNA

, 2.BBaseBmodification



AnticodonBbases,BandBnearbyBbases,BcanBbeBmodified

(Don'tBneedBtoBmemorizeBmodifications)



whyBareBtRNA'sBcleavedBduringBtheirBprocessingB-
BAnswerMoreBRNABtranscribedBthanBactuallyBneededBforBtRNABtoBfunction,BsoBtrimBit:



WhenBareBmRNABprocessedBinBeukaryotes?B-BAnswerinBtheBnucleus

modifiedBbeforeBexportBfromBtheBnucleusBtoBtheBcytoplasm



WhatBareBmainBmRNABprocessingBmodificationsB-BAnswer5'Bcap

3'BpolyBABtail



splicing;BremovalBofBintronsBfromBtheBmiddle



WhenBdoBallBtheBmRNABprocessingBeventsBoccur?B-
BAnswerRatherBthanBoccurringBasBindependentBeventsBfollowingBsynthesisBofBaBpre-
mRNA,BtheseBprocessingBreactionsBareBcoupledBtoBtranscriptionBsoBthatBmRNABsynthesisBand
BprocessingBareBcloselyBcoordinatedBstepsBinBgeneBexpression.



WhatBmaintainsBtheBcoupledBmRNABprocessingBmodificaitonsBevents?B-BAnswer·BTheBC-
terminalBdomainB(CTD)BofBRNABpolymeraseBIIBplaysBaBkeyBroleBinBcoordinatingBtheseBprocess
esBbyBservingBasBaBbindingBsiteBforBtheBenzymeBcomplexesBinvolvedBinBmRNABprocessing.



TheBassociationBofBtheseBprocessingBenzymesBwithBtheBCTDBofBpolymeraseBIIBaccountsBforBt
heirBspecificityBinBprocessingBmRNAs;BpolymerasesBIBandBIIIBlackBaBCTD,BsoBtheirBtranscriptsB
areBnotBprocessedBbyBtheBsameBenzymeBcomplexes



HowBisBtheB5'BendBofBmRNABprocessedB-BAnsweradditionBofBaBstructureBcalledBaB7-
methylguanosineBcap.



·BCappingBisBinitiatedBbyBtheBadditionBofBaBguanosineBtriphosphateB(GTP)BinBreverseBorientati
onBtoBtheB5′BterminalBnucleotideBofBtheBRNA.