分子生物学分子生物学 (9).pdf

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1、Chapter 5Regulation of Gene Expression25.3 Characteristics and regulation of genomic DNA expression in eukaryotesCharacteristics of gene expression in eukaryotes(1)Pluripotency of cells(2)The character of temporality and spatiality of geneexpression(3)Transcription and translation are carried out se

2、parately5.3.1 Regulation of Gene Expression in EukaryotesCharacteristics of gene expression in eukaryotes(4)The primary transcription product will be processed and modified after transcription.The primary transcription product is heterogeneous nuclear RNA（hnRNA）(5)Multi-copies of certain genes.(6)Th

3、e mRNA of eukaryotic gene is monocistron.(1)Loss of chromatinIrreversible regulation.For example,somelower organisms(such as nematodes)losechromatin during the development ofsomatic cells.2020/5/1655.3.2 Regulation of genomic DNA expression in eukaryotes(2)Gene amplificationWhen the demand for the p

4、roducts of acertain gene increases,instead of regulatethe its activity,we can increase the copynumber of the gene.2020/5/166(3)Gene rearrangementVJCVJCVJCImmunoglobulin IgG gene rearrangementIt refers to the rearrangement and combination ofsome gene segments by changing the original existenceorder t

5、o become a complete transcription unit andregulate expression product diversity.2020/5/167A methylation(5mC)of a Cytosine occured aspecificCpG island The degreeofmethylation is relatedinversely to geneexpression.The higher degree of methylationis,the lower gene expression becomes.Demethylation increases gene expression.GCGCGCGCGene2020/5/168(4)Gene methylation2020/5/16(5)The regulation of chromatin structure on gene expressionOpen,euchromatinconfiguration,whichrepresents transcriptionally active chromatinis aunique regulatory mechanism prior totranscription.10