LacOperon

LacOperon - Transcriptional Regulation Regulation of Gene...

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1 Transcriptional Regulation 1 Regulation of Gene Expression ranscriptional inhibition/enhancement • Transcriptional inhibition/enhancement • mRNA degradation/stabilization • Translational inhibition/enhancement • Protein degradation/stabilization hibition/stim lation of protein f nction 2 • Inhibition/stimulation of protein function The Lac Operon: A Model of Transcriptional 3 Regulation Lactose Metabolism 4 Adapted from Fig 19.2
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2 Jacob and Monot: alactosidase expression is induced by the β -galactosidase expression is induced by the presence of lactose in bacterial growth media 5 β -Galactosidase Induction is Affected by Mutations in Five Complementation Groups ene: rotein/Phenotype Gene: Protein/Phenotype lacZ : Encodes β -galactosidase lacY : Encodes permease (originally thought to encode transacetylase) lacI : Inhibits lacZ, Y and A expression when lactose is absent O Mtt i i O i i l i f f tt 6 lacO : Mutations in O are similar in effect to mutations that inactivate the ability of LacI to regulate Z, Y , and A expression lacP : Required for lacY, Z, and A expression LacZ ,Y, and A are Located on a Polycistronic (Polygenic) mRNA 7 Fig 19.4 Lac operon polycistronic mRNA What is an Operon? system of gene regulation where multiple • A system of gene regulation where multiple genes are under control of a single promoter • Consists of a polycistronic mRNA and its regulatory elements • Genes in an operon typically function in a 8 py p y common metabolic pathway
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3 Polycistronic mRNAs Exhibit Polarity
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This note was uploaded on 05/17/2011 for the course MCDB 101A taught by Professor Thrower during the Spring '08 term at UCSB.

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LacOperon - Transcriptional Regulation Regulation of Gene...

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