Lac operon

  • Created by: vezting
  • Created on: 19-04-16 16:05
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  • lac operon and proteins
    • protein synthesis
      • can be controlled at a genetic level
        • by stopping an starting genes by switching them on or off
      • operons: genetically control the protein in prokaryotes
        • an operon is a section of DNA that control structural genes, control elements and sometimes a regulatory gene
      • factors that start transcription are called activators and those that stop it are called repressors
    • E.coli lac operon
      • e.coli is a bacterium that respires using glucose but can use lactose if glucose isnt present
      • the genes that produce the enzymes needed to respire lactose are found on the lac operon
      • lactose not present
        • 1:regulatory gene produces the lac repressor
        • 2: repressor binds to operator site blocking the promotor site
        • 3: RNA polymerase cant bind to this site, meaning no transcription
      • lactose present
        • 1: lactose binds to a site on the repressor, which is in the operator binding site
        • 2: this causes repressor to chnage shape and dissociate with the operator region
        • 3: promotor region is unblocked
        • 4: RNA polymerase binds to operator site and transcription of genes Z and Y can start
        • 5: these genes are transcribed into Beta Galactisodase and lactose permease.
        • 6: lactose permease takes up the lactose and converts to glucose uning B Galac.


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