Gene Expression in Prokaryotes and Eukaryotes

What is the role of feedback inhibition in the regulation of enzyme activity?

• It enhances enzyme activity.

• It inhibits enzyme activity.

• It has no effect on enzyme activity.

• It promotes gene expression.

When is the trp repressor active?

• In the absence of tryptophan

• In the presence of tryptophan

• When the operon is on

• When the operon is off

What is the result of the trp operon being turned off?

• Tryptophan synthesis continues.

• No mRNA is made.

• RNA polymerase binds more efficiently.

• Protein synthesis increases.

What is the effect of an inducer on transcription in an inducible operon?

• It shuts off transcription

• It turns on transcription

• It has no effect

• It decreases transcription

What molecule inactivates the repressor to turn the lac operon on?

• Repressor

• Inducer

• Activator

• Enhancer

What is the function of the genes in the lac operon?

• Code for enzymes for lactose metabolism

• Code for enzymes for glucose metabolism

• Code for enzymes for protein synthesis

• Code for enzymes for DNA repair

What happens to the lac operon when lactose is absent?

• Operon is on, mRNA is made.

• Operon is off, no mRNA is made.

• Operon is on, proteins are synthesized.

• Operon is off, proteins are synthesized.

Which part of the lac operon does the repressor bind to?

• Promoter

• Operator

• lacZ gene

• lacY gene

What is the relationship between lactose presence and repressor activity in the lac operon?

• Lactose activates the repressor

• Lactose inactivates the repressor

• Lactose has no effect on the repressor

• Lactose degrades the repressor

What happens to the lac operon when the repressor is inactive?

• The operon is off

• The operon is on

• RNA is not made

• Protein is not synthesized