Purpose & Organization of the Lac Operon

What is the primary role of the Lac operon in bacteria?

• To regulate glucose metabolism

• To synthesize amino acids

• To regulate lactose metabolism

• To produce energy from proteins

Which protein facilitates the transport of lactose into the bacterial cell?

• RNA polymerase

• Beta-galactosidase

• Galactoside transacetylase

• Lactose permease

What is the function of beta-galactosidase in the Lac operon?

• To transport lactose into the cell

• To bind to the operator region

• To acetylate toxic galactosides

• To split lactose into glucose and galactose

What is the hypothesized role of the LacA gene product?

• Binding to the promoter region

• Transporting lactose into the cell

• Excreting toxic galactosides

• Splitting lactose into glucose and galactose

How does allolactose affect the Lac repressor?

• It increases cyclic AMP levels

• It activates the Lac repressor

• It inhibits the Lac repressor

• It binds to the CAP protein

What happens to cyclic AMP levels when glucose is abundant?

• They increase

• They decrease

• They fluctuate randomly

• They remain unchanged

In the presence of both lactose and glucose, why is transcription of the Lac operon negligible?

• Because allolactose inhibits the Lac repressor

• Because RNA polymerase is overactive

• Because cyclic AMP levels are high

• Because CAP cannot bind without cyclic AMP

Why is glucose the preferred energy source for bacteria over lactose?

• It requires fewer enzymes

• It is more energy-efficient

• It is easier to metabolize

• It is more abundant

What occurs when only glucose is available to the bacteria?

• The Lac operon is partially activated

• The Lac operon is fully activated

• The Lac operon is unaffected

• The Lac operon is completely inhibited

What is required for maximal transcription of the Lac operon genes?

• High glucose levels

• CAP bound to the CAP binding region

• Absence of lactose

• Lac repressor bound to the operator