Operons

In negatively regulated operon the bound repressor will

• inhibit transcription

• Enhance the activity of RNA polymerase

• Facilitate transcription

• Decrease the enzymatic ectivity of RNA polymerase

Which of these operons is anabolic?

• Lac

• Ara

• Trp

• Phe

Which of these systems give the best mode for turning trp operon off?

• Repressor

• Attenuator

• Repressor with a downstream poly A tail

• Repressor with an attenuator

A Lac repressor is a tetramer repressed when bound to the inducer. The trp repressor is a ____________________

• Dimer inactivated when bound to the inducer

• Dimer activated on inducer binding

• Tetramer inactivated on inducer binding

• Tetramer activated on inducer binding

The lactose operon is likely to be transcribed when

• there is more glucose in the cell than lactose.

• the cyclic AMP levels are low.

• there is glucose but no lactose in the cell.

• the cyclic AMP and lactose levels are both high within the cell.

• the cAMP level is high and the lactose level is low.

Tags

NGSS.HS-LS1-3

A lack of this nonprotein molecule would result in the inability of the cell to "turn off" genes:

• Operon

• Inducer

• Promoter

• Repressor

• Corepressor

In the absence of an inducer, gene expression of an inducible promoter will be

• on

• off

• halfway on

When uncharged tRNA concentration is low what will you expect as the activity of tryptophan operon?

• Low

• Medium

• High

• Very high

We know that lactose has a positive impact on the activity of the lac operon. Tryptophan’s presence has a ________________

• Positive feedback

• Negative feedback

• No difference

• Highly positive impact

Tags

NGSS.HS-LS1-3

Which segments of the attenuator together form the repression loop?

• Segment 1-2

• Segment 2-3

• Segment 3-4

• Segment 1-4