Question

Explain how gene regulation occurs using the lac operon as an example.

Answer 1

The process of turning genes on and off is known as gene regulation. These proteins bind to regulatory regions of a gene and increase or decrease the level of transcription. By controlling the level of transcription, this process can determine the amount of protein product that is made by a gene at any given time.

The lactose operon is an operon required for the transport and metabolism of lactose in E.coli and many other enteric bacteria. This operon contains genes coding for proteins in change of transporting lactose into the cystol and digesting it into glucose. This glucose is then used to make energy.

The activity of the promoter that controls the expression of the lac operon is regulated by two different proteins. One of the protein prevents the RNA polymerase from transcribing, the other enhances the binding of RNA polymerase to the promoter.

A repressor protein binds the operator (control) region upstream of the operon preventing transcription. When lactose is present outside the cell, it crosses the cell membrane and acts as an inducer of the operon.CAP promotes RNA polymerase transcription of genes leading to an increase of lac operon expression.

The regulatory gene lacl produces an mRNA that produces a Lac repressor protein, which can bind to the operator of the lac operon.