8 Gene Regulation Free Online FlashCards

What is gene regulation?

Gene regulation controls when, where, and how much a gene is expressed.

What is a promoter?

A promoter is a DNA region where RNA polymerase and associated proteins assemble to begin transcription.

What does an operator do?

An operator is a DNA site, commonly found in bacterial operons, where a repressor can bind and block transcription.

What is an enhancer?

Enhancers are regulatory DNA sequences that bind activators and increase transcription; they can be far from the genes they regulate.

What is a silencer?

Silencers bind regulatory proteins that reduce transcription, sometimes by interfering with activators or transcription machinery.

How do cis-acting and trans-acting regulators differ?

Cis-acting sequences affect genes on the same DNA molecule; trans-acting proteins can be made elsewhere and diffuse to their binding sites.

What is an operon?

An operon is a group of related genes controlled by a single promoter and transcribed together into one RNA molecule.

What happens to the lac operon when lactose is absent?

When lactose is absent, the Lac repressor binds the operator and prevents substantial transcription of the lac operon.

How does allolactose affect the Lac repressor?

Allolactose binds the Lac repressor and causes it to release the operator, allowing transcription of the lac operon.

How does low glucose promote lac operon transcription?

Low glucose raises cAMP; cAMP binds CAP, which helps RNA polymerase initiate transcription. The lac operon is expressed most strongly when lactose is also available.

How does tryptophan regulate the trp operon?

The trp operon is transcribed when tryptophan is scarce. When tryptophan accumulates, it enables the repressor to bind the operator and shut down transcription.

What do general transcription factors do at eukaryotic promoters?

General transcription factors help recruit RNA polymerase to eukaryotic promoters.