Quick 10Q: Operons

Front

What is an operon?

Back

An operon is a cluster of genes under the control of a single promoter, which are transcribed together and regulated as a unit.

Front

What is a repressible operon?

Back

A repressible operon is one that is normally active but can be turned off by a molecule binding to a repressor.

Front

What is an inducible operon?

Back

An inducible operon is one that is normally inactive but can be turned on by the presence of a specific molecule.

Front

What role does the repressor play in an operon?

Back

The repressor is a protein that binds to the operator region of an operon to inhibit transcription.

Front

What is the function of the operator in an operon?

Back

The operator is the site where the repressor binds, acting as an on/off switch for transcription.

Front

What happens when tryptophan is present in the trp operon?

Back

Tryptophan binds to the repressor, activating it, which then binds to the operator to turn transcription off.

Front

What happens when lactose is present in the lac operon?

Back

Lactose binds to the repressor, inactivating it, which allows transcription to occur.

Front

What is a corepressor?

Back

A corepressor is a molecule that binds to a repressor protein, activating it to inhibit transcription.

Front

What is an inducer?

Back

An inducer is a molecule that binds to a repressor, inactivating it and allowing transcription to proceed.

Front

What is the significance of the promoter in an operon?

Back

The promoter is the region where RNA polymerase binds to initiate transcription of the operon.