The lac operon in E. coli consists of genes that code for enzymes necessary for the breakdown of lactose. When lactose is absent, the operon is inactive because a repressor protein binds to a specific site in the lac operon. When lactose is present, lactose molecules bind to the repressor protein, causing the repressor protein to dissociate from the binding site. In the absence of glucose (a preferred energy source for bacteria), the protein CAP binds to a regulatory site near the lac promoter to activate transcription of the lac operon.

The lac operon in E. coli contains genes that code for enzymes necessary for the breakdown of lactose. It is expressed only in the absence of glucose is but when lactose is present . It has two regulators turn the operon "on" and "off" in response to the corresponding lactose and glucose levels: they are the lac repressor and catabolite activator protein (CAP).

Explanation:

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kasliwalalvi24 kasliwalalvi24 · Answer 2 · 2022-01-10T13:06:04+01:00

Lac Operon is an operon that takes place in the E.coli, which is required for the transport and metabolism of lactose.

The working of lac operon can be explained as:

In the lac operon, E.coli has the genes, which are involved in the metabolism of lactose. The gene can be expressed in the presence of lactose.

The regulators 'on' and 'off' work in response to the lactose and glucose levels. The regulators are lac repressor and catabolite activator protein.
The lac repressor acts as a lactose sensor, which normally blocks the transcription of the operon in the absence of lactose.
Catabolite Activate Protein is a glucose sensor, which activates the transcription of the operon when the levels of glucose are low.

Thus, the CAP protein binds to the regulatory site that is present near the lac promotor for activating the transcription of the lac operon.

To know more about lac operon, refer to the following link:

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