What is lac operon How is the operator switch on and off in the gene expression of the operon?

Lac operon contains genes involved in metabolism. The genes are expressed only when lactose is present and glucose is absent. The operon is turned on and off in response to the glucose and lactose levels: catabolite activator protein and lac repressor. The lac repressor blocks the transcription of the operon.

How does lac operon switch on?

The repressor protein binds to the operator region of the operon and prevents RNA polymerase from transcribing the operon. In the presence of an inducer, such as lactose or allolactose, the repressor is inactivated by interaction with the inducer. Thus, the lac operon gets switched on.

How is the operon switched off?

The operon is switched off when repressor protein produced by regulator or inhibitor gene binds to operator gene and prevents RNA polymerase from transcribing the operon.

What does the lac operon consist of how is the operator switch turned on and off in the expression of genes in this operon explain 5 33?

The lac operon consists of series of three genes in bacteria that produce the necessary enzymes to metabolise lactose and it also contains promotar and terminator regions. The three genes are lacZ, lacY and lacA. This protein will bind to the operator region of the lac operon until molecules of lactose bind to it.

What is the function of the lac operator?

What is the function of the lac operator? It produces the lac repressor protein.

Which of the following regulate switching on and off of lac operon?

Lactose is the substrate for the enzyme beta galactosidase and it regulates switching on and off of the operon. It is termed as inducer.

Why is the lac operon normally off?

Normally, the lac operon is turned off. This operon takes the stage when glucose levels are low. This is because of another protein, called catabolite activator protein (CAP), and cyclic adenosine monophosphate (cAMP) molecules.

Why does lac operon shut down?

After addition of lactose complete breakdown of lactose to glucose and galactose takes place. Therefore there is no more lactose to bind to the repressor protein and the lac operon shuts down.

What is the function of lac A?

The lac z gene encodes beta-galactosidase, the lac y gene encodes a permease, and the lac a gene encodes the transacetylase enzyme. Together, these gene products act to import lactose into cells and break it down for use as a food source.

What is the function of the operator in the lac operon quizlet?

The function of the lac operator is to bind the lac repressor, preventing transcription of the lac operon. The lac promoter binds RNA polymerase initiating transcription of the lac operon. Beta-galactosidase cleaves the dissacharide lactose, found in milk, into galactose and glucose.