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