基因表达及调控ppt课件.ppt

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1、SynthesisandProcessingoftheProteinTheRoleoftheRibosomeinProteinSynthesisRibosomescoordinateproteinsynthesisbyplacingthemRNA,aminoacyl-tRNAsandassociatedproteinfactorsintheircorrectpositionsrelativetooneanother.Componentsofribosomes,includingtherRNAs,catalyzeatleastsomeofthechemicalreactionsoccur

2、ringduringtranslation.rRNAsprovideascaffoldingwithintheribosome,towhichtheproteinsareattachedThecloverleafstructureofatRNAtRNA在蛋白合成中的作用physicallinkinformationallinkTheribosomebindingsiteforbacterialtranslationInitiationoftranslationinbacteria真核生物的翻译启始RegulationoftranslationinitiationGlobalregula

3、tion,whichinvolvesageneralalterationintheamountofproteinsynthesisoccurring,withallmRNAstranslatedbythecapmechanismbeingaffectedtoasimilarextent.Transcript-specificregulationinvolvesmechanismsthatactonasingletranscriptorasmallgroupoftranscriptscodingforrelatedproteins.Transcript-specificregulatio

4、noftranslationinitiation.(A)Regulationofribosomalproteinsynthesisinbacteria.(B)Regulationofferritinproteinsynthesisinmammals.ElongationoftranslationTerminationoftranslationElongationoftranslationinEscherichiacoli蛋白质的翻译后加工ProteinfoldingNotallproteinsfoldspontaneouslyinthetesttube.Incells,foldingi

5、saidedbymolecularchaperones（分子伴侣）.Molecularchaperonesdonotspecifythetertiarystructureofaprotein,theymerelyhelptheproteinfindthatcorrectstructure.有些真核基因在原核细胞中表达不能正确折叠。beevenomProcessingbyproteolyticcleavageinsulinProcessingbychemicalmodificationAcetylation,Glycosylation,phosphorylationOver150diff

6、erentmodifiedaminoacidshavebeendocumentedindifferentproteinsInteinsplicingMostareknowninbacteriaandarchaeabuttherearealsoexamplesinlowereukaryotes.Inafewcasesthereismorethanoneinteininasingleprotein.ProteinDegradationIneukaryotes,mostbreakdowninvolvesasinglesystem,involvingubiquitinandtheproteas

7、ome.RegulationofGenomeExpressionGenome≠TranscriptomeTwolevelsofgeneregulation1.是否表达2.表达量及表达后修饰基因表达调控的关键步骤是转录启始，即决定一个基因是否表达。基因组表达活性的调节一过性的表达活性改变永久或半永久性的表达改变（underliecellulardifferentiation）一过性的表达改变主要表现为对外界刺激的反应单细胞生物stimuli:nu