An inducer
In an inducible operon, the structural genes are transcribed only when an inducer molecule is present. The inducer molecule binds to the repressor protein, causing it to be released from the operator region. This allows the RNA polymerase to bind to the promoter region and initiate transcription of the structural genes.
An operon typically has one promoter, which initiates the transcription of the genes within the operon.
If the repressor could not bind the operator, it would be unable to inhibit the transcription of the operon. This would lead to continuous expression of the operon, regardless of the presence or absence of the inducer. This could result in a constant production of the operon's gene products.
One clue that the lac operon is on is the presence of lactose in the environment. The lac operon is induced when lactose is available as a substrate for the lac repressor protein, allowing transcription of genes involved in lactose metabolism.
The lac operon is shut off when lactose is absent. In the absence of lactose, the repressor protein binds to the operator site, preventing transcription of the lac operon genes.
A repressible operon is a type of operon in bacteria where gene expression is usually active but can be turned off when a specific corepressor molecule binds to the repressor protein. This binding causes the repressor to bind to the operator region of the operon, blocking transcription and thus shutting down gene expression. An example of a repressible operon is the trp operon in E. coli, which is involved in tryptophan biosynthesis.
In an inducible operon, the structural genes are transcribed only when an inducer molecule is present. The inducer molecule binds to the repressor protein, causing it to be released from the operator region. This allows the RNA polymerase to bind to the promoter region and initiate transcription of the structural genes.
False. The lac operon is an inducible operon, not a repressible one. It is typically turned off when lactose is absent and activated when lactose is present, allowing the transcription of genes needed for lactose metabolism. In contrast, repressible operons are usually active and can be turned off by the presence of a specific molecule.
An operon typically has one promoter, which initiates the transcription of the genes within the operon.
The operon often controls the transcription of prokaryote genes.
it blocks the promoter from the operon.
If the repressor could not bind the operator, it would be unable to inhibit the transcription of the operon. This would lead to continuous expression of the operon, regardless of the presence or absence of the inducer. This could result in a constant production of the operon's gene products.
The lac operon encodes enzymes required in the digestion and transport of lactose. Transcription is activated when there is lactose in the cellular environment, and RNA polymerase binds to the promoter region of the operon, and activates the expression of lacA, lacZ and lacY.
One clue that the lac operon is on is the presence of lactose in the environment. The lac operon is induced when lactose is available as a substrate for the lac repressor protein, allowing transcription of genes involved in lactose metabolism.
Operon
The expression of the tryptophan operon is controlled by a repressor protein that binds to the operator region in the presence of tryptophan. When tryptophan levels are high, the repressor is active and prevents transcription of the operon. When tryptophan levels are low, the repressor is inactive, allowing transcription to occur.
gene expression occurring at transcription