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History of genetics
Learn introductory genetics with Braimy- B.Sc agriculture
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  • RNA polymerase attaches to promoter site and then transcription proceeds in 5’ to 3’ direction beginning with operator site (O).
  • The regulator site regulates the synthesis of 3 enzymes and produces a repressor protein of 360 AA residue.
  • In absence of lactose, repressor protein binds to wild operator (O+) and prevents attachment of RNA polymerase to promoter. Hence, transcription is prevented.
  • In Presence of lactose, RNA polymerase binds to repressor and hence preventing it from binding to operator and hence all 3 genes are transcribed.
  • Finally, transcription is imitated in the operator site.

lac operon - Wikipedia

Explain with the help of schematic representation, the lac operon in  E-Coli. - Sarthaks eConnect | Largest Online Education Community

  • Turning on of lactose operon is done by catabolite receptor protein (CRP) bind to molecules of cyclic adenosine monophosphate (CAMP).
  • This enhances RNA polymerase binding and consequent transcription of the lac operon.
  • Presence of glucose interferes the production of CAMP and hence halts transcription of the lac operon.
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