Operons

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

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

• Low

• Medium

• High

• Very high

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

• on

• off

• halfway on

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

Which of these properties do not agree with trp operon attenuator?

• It brings about repression of trp operon

• It consists of one stem loop system

• It has two codons for tryptophan in sequence

• Ribosome stalls at the attenuator

Which of the Ara operon regulation site is actually preventing RNA polymerase from binding and producing the Ara genes BAD?

• O1

• O2

• P

• Z

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