What does lac operon produce?

What does lac operon produce?

The classic example of prokaryotic gene regulation is that of the lac operon. This operon is a genetic unit that produces the enzymes necessary for the digestion of lactose (Fig. 16-13). The lac operon consists of three contiguous structural genes that are transcribed as continuous mRNA by RNA polymerase.

What is the lac operon most active?

The lac operon is most active when lactose is high and glucose is low in the cell.

What does lac operon respond to the presence of?

The first control system for enzyme production worked out at the molecular level described the control of enzymes that are produced in response to the presence of the sugar lactose in E. coli cell.

How is the lac operon induced?

When lactose is available, some molecules will be converted to allolactose inside the cell. Allolactose binds to the lac repressor and makes it change shape so it can no longer bind DNA. Allolactose is an example of an inducer, a small molecule that triggers expression of a gene or operon.

How would lac operon operates in in E coli?

Answer : When lactose is present , the lac genes are expressed because allolactose binds to the lac repressor protein and keeps it from binding to the lac operator. Small amount of allolactose are formed when lactose enters E. coli.

What takes place during transcription?

Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA). The newly formed mRNA copies of the gene then serve as blueprints for protein synthesis during the process of translation.

What is operon explain the working principle of lac operon?

Mechanism of lac operon : In the absence of inducer lactose, the regulator gene R produces a repressor protein which binds to the operator site and prevents transcription of structural genes. When inducer lactose is introduced in the medium, it binds to the repressor and prevents it from binding to the operator.

How is the lac operon regulated?

Regulation of the lac Operon The activity of the promoter that controls the expression of the lac operon is regulated by two different proteins. One of the proteins prevents the RNA polymerase from transcribing (negative control), the other enhances the binding of RNA polymerase to the promoter (positive control).

What activates the lac operon?

The lac operon is an inducible operon that utilizes lactose as an energy source and is activated when glucose is low and lactose is present.

How does a lac operon operate?

In the lac operon, the presence of lactose acts as an inducer. – The promoter (p) is the site at which RNA polymerase binds to initiate the transcription of the structural genes. Thus, the lac operon gene is inactivated. – Lac operon in presence of an inducer binds with repressor protein and inactivates it.

What is the lac operon and how is it controlled?

The lac operon is a negatively controlled inducible operon, where the inducer molecule is allolactose. In negative repressible operons, transcription of the operon normally takes place. Repressor proteins are produced by a regulator gene, but they are unable to bind to the operator in their normal conformation.

What is the function of the lac operator?

Lac operator. The lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available.

How is the lac operon turned on and off?

The protein that is formed by the lacI gene is known as the lac repressor. The type of regulation that the lac operon undergoes is referred to as negative inducible, meaning that the gene is turned off by the regulatory factor (lac repressor) unless some molecule (lactose) is added.

What occurs during activation of the lac operon?

An operon is a functional set of genes that are located next to each other and are co-transcribed in prokaryotes. Describe what occurs during activation of the lac operon. A lactose molecule is used to deactivate the lac repressor gene, which allows the transcription of RNA to make enzymes to break down lactose.

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