Respuesta :

Answer: Lactose is necessary for transcription process.

Explanation:

When there is no lactose provided to the E.coli molecule then the lac repressor cling to the operator, and it prevents the transcription process conducted by the RNA polymerase enzyme. But in the presence of lactose the lac repressor does not bind to the operator which allows the RNA polymerase to actually transcribe the lac operon.

luisvaschetto

When E. coli is grown in a medium containing no glucose but abundant lactose, then neither CAP nor the lac repressor are bound to the DNA.

  • The lac operon is a cluster of prokaryotic genes having a single promoter which is transcribed as a single polycistronic messenger RNA (mRNA) involved in using lactose as a source of energy.

  • Moreover, the lac repressor is a protein that represses the transcription of the lac operon.

  • When lactose concentration is too low, the lac repressor binds with the operator to prevent transcription.

  • Catabolite activator protein (CAP) acts as a sensor of the glucose level.

  • When glucose concentration is too low, then CAP binds to the promoter of the lac operon to produce this molecule.

In conclusion, when E. coli is grown in a medium containing no glucose but abundant lactose, then neither CAP nor the lac repressor are bound to the DNA.

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