Inducible Operon

The lac operon is an example of an inducible operon. Which of the following describes the process that occurs when lactose is present?

• The lactose binds to the repressor which inactivates it and the repressor binds to the operator to turn translation on.

• The lactose binds to the repressor which activates it and the repressor releases from the operator to turn translation on.

• The lactose binds to the repressor which inactivates it and the repressor releases from the operator to turn translation on.

• The lactose binds to the repressor which activates it and the repressor binds to the operator to turn translation on.

In the lac operon the inducer is

• allolactose

• glucose

• galactose

• all of the above

What is 1 in the diagram?

• RNA polymerase

• Inducer

• Repressor

• Operator

What is 4 in the diagram?

• RNA polymerase

• Inducer

• Repressor

• Operator

What is the role of operons in prokaryote gene expression?

• It makes the genes prokaryotes be turned on

• It accounts for the regulation of gene activity in response to the needs of the cells

• To make DNA for the gene

• To make the gene turn of and off

Match the following genetic regions to their roles:

• Genes of Operon

• Codes for the main protein / enzymes

• Operator

• Makes a repressor protein

• Regulatory gene

• The on/off switch where the repressor protein binds

• Promotor

• Place where transcription begins

A protein that binds to the operator and blocks the RNA polymerase

• regulator

• repressor

• activator

• corepressor

The lac operon is referred to as a(n) __________ operon.

• inducible

• repressible

• audible

• inaudible

Which of the following best describes an inducible operon?

• A) An operon that is always active unless a repressor is present.

• B) An operon that is usually off but can be turned on by an inducer.

• C) An operon that is always inactive unless an activator is present.

• D) An operon that is always on regardless of environmental conditions.

In the context of the lac operon, what role does allolactose play?

• A) It acts as a repressor.

• B) It acts as an inducer.

• C) It acts as a corepressor.

• D) It acts as an activator.