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Review of the Lac Operon & Trp Operon definitions

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  • Lac Operon
    A DNA segment with three genes for lactose metabolism, controlled by an inducible regulatory system.
  • Trp Operon
    A DNA segment with five genes for tryptophan synthesis, regulated by a repressible system.
  • Inducible Operon
    A gene cluster typically off but can be activated by a specific molecule, allowing transcription.
  • Repressible Operon
    A gene cluster usually on but can be switched off by a regulatory molecule, halting transcription.
  • LacZ
    A gene within a lactose-metabolizing operon, essential for breaking down lactose into usable energy.
  • LacY
    A gene in the lactose operon, involved in transporting lactose into the bacterial cell.
  • LacA
    A gene in the lactose operon, contributing to lactose metabolism through enzymatic modification.
  • TrpA
    A gene in the tryptophan operon, encoding an enzyme subunit for tryptophan biosynthesis.
  • TrpR
    A regulatory gene encoding a protein that can repress the tryptophan operon when activated.
  • LacI
    A regulatory gene encoding a protein that binds the operator to block transcription in the absence of lactose.
  • Allolactose
    A lactose-derived molecule that binds and inactivates the repressor, enabling transcription of the lactose operon.
  • Corepressor
    A small molecule, such as tryptophan, that activates a repressor protein to inhibit gene expression.
  • Repressor Protein
    A regulatory protein that binds to an operator sequence, blocking RNA polymerase and preventing transcription.
  • Operator
    A DNA region where a regulatory protein binds to control access of RNA polymerase to structural genes.
  • Transcription
    The process of synthesizing RNA from a DNA template, regulated by operon systems in bacteria.