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ExplainhowRNApolymeraserecogniseswheretranscriptionshouldbegin
AspecificnucleotidesequencecalledapromoterallowsRNApolymerasetorecognisethe
siteoftranscription.
DescribetheroleofthepromoterandtheTATAbox
EukaryoticpromoterscontainasequencecalledaTATAboxwhichiscentredupstreamfrom
thetranscriptionalsite.Transcriptionproteinsbindtothispromoterinitiatingtranscription
byformingatranscriptioninitiatingcomplexwhichcausestheunwindingoftheDNA.
Whatisthefunctionalsignificanceofintrons?
IntronsarethenoncodingregionsoftheRNAthatissplicedoutbyaspliceosomeandleftin
thenucleusinmRNAmodification.Thesplicingofdifferentsectionsallowsdifferent
proteinstobeformedthereforecontrollinggeneexpression.Ifageneisswitchedoffitis
splicedoutandleftinthenucleussonotranslationcanoccur.
HowisRNAmodifiedaftertranscriptionineukaryoticcells?
ThemRNAiscappedandtailed.This5’capallowsrecognitionfortranslationalmachinery
whilethepolyAtailpreventsdegradation.
Whatisacodonanddescribeitsrelationtothelinearsequenceofthepeptidechain?
Acodonisasequenceof3basesonanmRNAmoleculethatcodesforaspecificaminoacid.
EachaminoacidonapeptidechaincorrelatestothecodonsequenceofthemRNA
molecule.
Whatdoesitmeanwhenitissaidthatthegeneticcodeisredundantandunambiguous?
Unambiguousreferstothefactthateachcodononlycodeforonespecificaminoacidsand
noothers.Theideaofredundancyreferstothefactthatmorethanonecodoncancodefor
thesameaminoacidsincethereareonly20andmanycombinationsofcodons.
Whatisthesignificanceofwobble?
Wobbleallowsthelastbaseofthecodontomatchwithanotherbasethatisnot
complementaryifityieldsthesameaminoacid.
Explaintheprocessoftranslationincludinginitiation,elongationandtermination
Initiation:themRNAbindstothesmallribosomalsubunitandtRNAcarryingthestartcodon
AUGattachestothepsitesignallingthelargeribosomalsubunittobindinordertoformthe
initiationcomplex
Elongation:TheaminoacyltRNAbindstotheAsiteandpeptidebondsareformedbetween
theaminoacidinthePsiteandAsitebypeptidyltransferaseandtheaminoacidit
transferredtothetRNAintheAsiteandthetRNAsmovethroughlikeaconveyerbelt.
Translocation:whentheAsitemeetsastopcodonareleasefactornotcarryinganamino
acidiscalledtothesitewhichlysesthebondingofthetRNAandpeptidechain.
HowistRNAjoinedwithanappropriateaminoacid?
Aminoacylsynthase
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Defineagene,componentsandroleingeneexpression
Agenehastwoparts,apromoterandcodingsequence.Thepromotorinitiatestranscription
andthecodingsequenceisthepartofthegenethatistranscribed.Ageneistheentire
nucleicacidsequenceneededforthesynthesisofanRNAsequence.
WhatarethetwotypesofsmallscaleDNAmutations?
1. Substitution–sicklecellanaemia
2. Insertion/Deletion
Defineasilent,missenseandnonsensemutation
Silent–hasnoeffectontheaminoacidproducedbecauseoftheredundancycode
Missense–stillcodesforanaminoacidbutthewrongone
Nonsense–codesforaprematurestopcodon
Describethegenotypicandphenotypiceffectsofsicklecell
ItisasubstitutionmutationwhichcausesRBCstobecomesickleshapedcausingthemto
becomelodgedincapillaries.ThisisbecausethesubstitutedAAcausedaproteinthatcodes
foramutationofthebetachainonhaemoglobin
Whydoesgeneticvariationindrugmetabolisinggenesimpactontheeffectsofdrugs?
Theabilitytometaboliseadrugdictateshowlongthedrugremainsinthebody.Ifadrug
hascertainsideeffectspeoplewithgenesthatdonometaboliseproperlythesideeffects
areprolongedandamplifiedsincetheyremaininthebody.Ifthisisthecaseasmaller
dosageofthedrugshouldbeadministered.
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