分子生物学教学资料第7章翻译

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1、Topic1mRNA1-1polypeptidechainsarespecifiedbyORF—-containstartcodonandendcodonEukaryoticmRNA（monocistrionic,单顺反子）ProkaryoticmRNA（polycistrionic,多顺反子）原核生物mRNA结构特点—ProkaryoticmRNAshavearibosomebindingsite（核糖体结合位点）thatrecruitsthetranslationalmachinery（核糖体）—16srRNAisthekeyfactordeterminingthetra

2、nslationEukaryoticmRNAaremodifiedattheir5'and3'endstofacilitatetranslationThe"cap”:amethylatedguaninejoinedtotheRNAtranscriptbya5"-5"linkage（甲基化的鸟H票吟）usesamethylatedcaptorecruittheribosome.Oncebound,theribosomescansthemRNAina5，-3"directiontofindtheAUGstartcodon…scanning（扌HI描）Kozaksequence:5

3、-G/ANNAUGG-3stopgZZZ«AAAAAn395*NNNNNGNN31start■Poly-Ainthe3fendpromotestheefficientrecyclingofribosomes,thusincreasingthetranslationefficiencyTopic2:tRNAtRNAareadaptorsbetweencodonsandaminoacidsPseudouridine（U,假尿卩密噪）isamodifiedbase.ThesemodifiedbasesintRNAleadtoimprovedtRNAfunctionAminoacid

4、sshouldbeattachedtotRNAfirstbeforeaddingtopolypeptidechaintRNAsarechargedbyattachmentofanaminoacidtothe3’terminalAofthetRNAviaahighenergyacyllinkage（高能酰基）AminoacyltRNAsynthetaseschargetRNAintwosteps:Adenylylation（腺昔酰化）ofaminoacids;tRNAcharging;polypeptideOverviewoftheeventsofribosomecycleCo

5、pynghtO2004PearsonEducation.Inc.,publishinga$BenjaminCummingsTopic4:theribosomeThelargesubunitcontainsthepeptidyltransferasecenter（肽基转移酶中心）responsiblefortheformationofpeptidebondsassociatewitheachotherandtranslatethemRNA,thendissociateaftereachroundoftranslationThesmallsubunitinteractingwit

6、hrnRNAcontainsthedecodingcenter（解码中心）chargedtRNAsreador“decode”thecodonunitsofthemRNA.N/N-terminal誓RibosomalRNAs（rRNA）arebothstructuralandcatalyticdeterminantsoftheribosomes4-6TheribosomehasthreebindingsitesfortRNAunchargedtRNAAsite:tobindtheaminoacylated-tRNAP-site:tobindthepeptidyLtRNAE-s

7、ite:tobindtheTopic5:InitiationoftranslationThreeeventsmustoccur:1.ribosomemustberecruitedtomRNA2.achargedtRNAmustbeplacedintothePsiteofribosome3.theribosomemustbepreciselypositionedoverthestartcodon原核牛物翻译:5-2AspecializedtRNAchargedwithmodifiedmethionineb