Prokaryotic Gene Regulation

Free Response

Describe how transcription in prokaryotic cells can be altered by external stimulation such as excess lactose in the environment.

Hint:

Environmental stimuli can increase or induce transcription in prokaryotic cells. In this example, lactose in the environment will induce the transcription of the lac operon, but only if glucose is not available in the environment.

What is the difference between a repressible and an inducible operon?

Hint:

A repressible operon uses a protein bound to the promoter region of a gene to keep the gene repressed or silent. This repressor must be actively removed in order to transcribe the gene. An inducible operon is either activated or repressed depending on the needs of the cell and what is available in the local environment.