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1、Chapter 5Regulation of Gene Expression5.1 The common characteristics of gene expression in prokaryotes and eukaryotesGenetic information,that is carried byspecific structural genes in the genomes ofprokaryotes and eukaryotes,goes througha series of processes such as transcriptionand translation,to s
2、ynthesize RNAs andproteins with specific biological.Gene expressionCharacteristics of gene expression(1)Temporal specificity Developmental stage specific(2)Spatial specificityTissues and cells specificCatagorized based on their responses to stimulus:(1)Basic/constitutive expressionModels of gene exp
3、ression(2)Stimulation-induced or-suppressed expressionThe regulation of gene expressionThe expressions and copy number of certaingenes varies according to different developmentstage,differentcells,andunderdifferentconditions,althoughtheycarrythesamegenetic information(the same structural gene)Regula
4、tory factors of gene expressionProteins(main regulatory factors)RNAs7Levels of gene expression regulation Genome Transcription Post-transcription Translation Post-translationThe central dogma of molecular biology:5.1.1 regulation of prokaryotic gene expression The regulation of prokaryotic gene expr
5、essionis primarily performed at transcriptional level,followed by translational level.In this section,we mainly used E.coli as anexample to introduce the regulation ofprokaryotic gene expression.Characteristics of gene expression in prokaryotes(1)Only one kind of RNA polymerase(2)Operon acts as the
6、basic unit during gene expression processesF.JacobJ.L.MonodOperon theory initiated a new era of gene expression regulation research.Operon modelppromoterRegulatory region Structural genes:multiple tandemayzstructural geneOperon:an operon is constituted by a polycistronic transcription unit and its r
7、egulatory sequences.PromoterGene 1Gene 2Gene 3TerminatorDNATranscriptionmRNA31235TranslationProteins123Prokaryotic mRNA is polycistronic mRNA(3)Transcription and translation are coupledwith each other.(4)The starting site of mRNA contains SDsequence.The common sequence isAGGAGG.(5)The regulation of prokaryotic gene expressionis predominantly performed at the transcriptionallevel(the regulation of RNA synthesis).Two general ways:Initiation regulation(promoter regulation);Termination regulation(attenuator regulation).
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