Regulation of lac operon

What is the lac operon?

• The lac operon is a genetic system in bacteria that controls the expression of genes involved in lactose metabolism.

• The lac operon is a type of protein found in plants.

• The lac operon is a structure in animal cells.

• The lac operon is a type of virus that infects bacteria.

What are the three structural genes in the lac operon?

• lacZ, lacY, lacA

• lacB

• lacD

• lacC

Which gene in the lac operon encodes for the enzyme beta-galactosidase?

• lacZ

• lacY

• lacA

• lacW

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

• Promotes the synthesis of lactose

• Cleaves lactose into glucose and galactose

• Inhibits the breakdown of lactose

• Converts glucose into lactose

What is the role of the lac repressor in the regulation of the lac operon?

• The lac repressor is only active when lactose is absent.

• The lac repressor is involved in translation of the lac operon.

• The lac repressor enhances transcription in the presence of lactose.

• The lac repressor acts as a negative regulator by blocking transcription in the absence of lactose.

What is the inducer of the lac operon?

• lactose

• fructose

• sucrose

• glucose

How does the inducer affect the lac repressor?

• The inducer degrades the lac repressor.

• The inducer enhances the binding of the lac repressor to the lac operator.

• The inducer prevents the lac repressor from binding to the lac operator.

• The inducer has no effect on the lac repressor.

What is the role of cAMP-CAP complex in the regulation of the lac operon?

• Inhibits RNA polymerase binding to the promoter

• Enhances RNA polymerase binding to the promoter

• Activates the lac repressor

• Decreases cAMP levels in the cell

Explain the concept of positive regulation in the lac operon.

• Positive regulation in the lac operon is achieved by the binding of an activator protein, like cAMP-CRP, to the regulatory region, which enhances RNA polymerase binding and increases transcription.

• Positive regulation in the lac operon is independent of any regulatory proteins

• Positive regulation decreases RNA polymerase binding and transcription

• Positive regulation is achieved by the binding of a repressor protein to the regulatory region

Describe the process of catabolite repression in the lac operon.

• Catabolite repression in the lac operon is the inhibition of lactose metabolism enzyme production in the presence of glucose, mediated by cAMP-CAP complex binding to the lac operon promoter.

• Catabolite repression is the activation of lactose metabolism enzyme production in the presence of glucose.

• Catabolite repression in the lac operon is mediated by the binding of RNA polymerase to the lac operon promoter.

• Catabolite repression occurs when lactose is absent in the lac operon.