《分子生物学》课程PPT教学课件（讲义）lect4 Control of Gene Expression 基因表达的调控

Control of gene expression 基因表达的调控

Control of Gene Expression 基因表达的调控

Necessity of gene expression 并非所有的基因都需要连续表达。不同 的细胞,不同的细胞周期,同一个基因 表达水平也不一样 为适应不断改变的生活环境 调控可以使生物在其所处的环境中以最 优的方式生存

Necessity of gene expression • 并非所有的基因都需要连续表达。不同 的细胞，不同的细胞周期，同一个基因 表达水平也不一样。 • 为适应不断改变的生活环境。 • 调控可以使生物在其所处的环境中以最 优的方式生存

Tow difference genes Housekeeping gene(管家基因):是一些细 胞维持正常细胞功能所需的基因,是连 续表达的 Regulated gene(可调节基因):它们的活性 是以细胞或生物体的需求来控制的

Tow difference Genes • Housekeeping Gene(管家基因): 是一些细 胞维持正常细胞功能所需的基因，是连 续表达的 • Regulated gene(可调节基因): 它们的活性 是以细胞或生物体的需求来控制的

Difference levels is gene expression regulated DNA rearrangements: programmed change of DNA Sequence position Transcriptional regulation: RNa synthesis RNA processing: splicing Stability of mRNA: half life Translational control: peptide synthesis Post translational control: enzymes

Difference Levels is Gene expression regulated • DNA rearrangements: programmed change of DNA sequence position. • Transcriptional regulation: RNA synthesis • RNA processing: splicing • Stability of mRNA: half life • Translational control: peptide synthesis • Post translational control: enzymes

Regulation of protein activity vs amount Regulate protein activity Allostery变构效应 Covalent modification Sequestration Regulate the amount of protein Gene transcription RNA processing RNa turnover mRNa translation Protein processing, assembly, turnover

Regulation of protein activity vs. amount • Regulate protein activity – Allostery变构效应 – Covalent modification – Sequestration • Regulate the amount of protein – Gene transcription – RNA processing – RNA turnover – mRNA translation – Protein processing, assembly, turnover

Difference between prokaryotic and eukaryotic regulation Transcription often is controlled at the stage of initiation. It may also be controlled at termination to prevent transcription from proceeding past a terminator to the gene(s) beyond. This is the primary control strategy for bacterial gene expression In eukaryotic cells, processing of the rna product may be regulated at the stages of modification, splicing, transport, or stability. In bacteria, an mRNa is in principle available for translation as soon as it is synthesized, and these stages of control are not avallable

Difference between prokaryotic and eukaryotic regulation • Transcription often is controlled at the stage of initiation. It may also be controlled at termination to prevent transcription from proceeding past a terminator to the gene(s) beyond. This is the primary control strategy for bacterial gene expression • In eukaryotic cells, processing of the RNA product may be regulated at the stages of modification, splicing, transport, or stability. In bacteria, an mRNA is in principle available for translation as soon as it is synthesized, and these stages of control are not available

Regulation of Transcription in Prokaryotes 原核生物转录的调控 Lactose Operon 乳糖操纵子 Jacob and monod

Regulation of Transcription in Prokaryotes 原核生物转录的调控 Lactose Operon Jacob and monod 乳糖操纵子

Key terms Cistron(顺反子Gene基因)是一段能编码多肽链的DNA,包括 前导肽 leader和尾随肽 trailer,以及分割编码区 exons的间隔序列 ˉ Operon(操纵子,操纵元):是细菌DNA中基因表达和调控的的 单元,包括结构基因和控制单元。 tructural gene(结构基因)编码任何RNA或 protein的DNA序列, product other than a regulator Repressor protein(阻遏蛋白):能够结合到 dNA or rna上阻断 transcription or translation Operator(调控元件)是一段DNA位点,它能结合 Repressor protein来阻断相邻 promoter的起始转录 Regulator gene(调节基因)能编码结合到特定DNA位点的蛋白质 来调控 transcription Corepressor辅阻遏物:使阻遏蛋白具有活性或使活性蛋白失去 活性的物质

Key Terms •Cistron(顺反子Gene 基因): 是一段能编码多肽链的DNA，包括 前导肽leader和尾随肽trailer，以及分割编码区exons的间隔序列。 •Operon (操纵子，操纵元):是细菌DNA中基因表达和调控的的 单元，包括结构基因和控制单元。 •Structural gene(结构基因): 编码任何RNA或 protein的DNA序列， product other than a regulator. •Repressor protein(阻遏蛋白): 能够结合到DNA or RNA上阻断 transcription or translation。 •Operator(调控元件):是一段DNA位点，它能结合 Repressor protein 来阻断相邻promoter 的起始转录。 •Rgulator gene(调节基因):能编码结合到特定DNA位点的蛋白质 来调控transcription。 •Corepressor辅阻遏物:使阻遏蛋白具有活性或使活性蛋白失去 活性的物质

Operons An operon is a cluster of coordinately regulated genes. It contains Structural genes: encode enzymes Regulatory genes: encode repressors or activators of expression Regulatory sites: e.g. promoters, operators

Operons • An operon is a cluster of coordinately regulated genes. It contains: • Structural genes: encode enzymes • Regulatory genes: encode repressors or activators of expression • Regulatory sites: e.g. promoters, operators

the lac operon Gene Controlling Terminator Promoter site Coding sequence DNA duction Transcription and translation occur only after induction Gene product Inducible genes are expressed only when induced Activator site Promoter (Polymerase Lac (CAP binding site) binding site) Operator Lac z L1 deletion

the lac Operon