Lac and Trp Operon

Which segments of the attenuator together form the repression loop?

• Segment 1-2

• Segment 2-3

• Segment 3-4

• Segment 1-4

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

In the absence of glucose, the binding of CRP-cAMP complex to the region near to the lac promoter will

• No significant effect on the transcription of lac genes

• Cause the release of RNA polymerase from the promoter

• Decrease transcription of lac genes

• Increase transcription of lac genes

The lac repressor have which of the following DNA binding motif

• Zinc Finger

• Homodomain

• Leucine zipper

• Helix-turn-helix

The functional lac repressor is a

• Dimer of identical monomers

• Tetramer of two identical dimers

• Tetramer of identical monomers

• Trimer of identical monomers

A ____ often controls the transcription of prokaryote genes.

• hox gene

• interfering RNA

• operon

• protein complex

When will a lac operon be activated?

• Glucose is low and lactose is present

• Glucose is high and lactose is absent

• both glucose and lactose is high

• both glucose and lactose is low

Bacterial genes are organized into

• promotors

• operons

• regulator genes

• structural genes

specific sequence within the DNA that bind transcription factors to turn transcription on or off

• Regulator

• Promotor

• Operator

• Structural genes

Inducible operon s

• lac operon

• trp open

• bound to a repressor under normal conditions

• similar to competitive inhibition