Lac Operon Function and Regulation

The video tutorial explains the concept of operons, focusing on the difference between repressor proteins and inducible operons. It uses the lac operon in E. coli as a primary example, illustrating how the presence of lactose can activate gene transcription by causing the repressor to detach, allowing RNA polymerase to transcribe the necessary genes for lactose digestion. The tutorial highlights the role of lactose in gene activation and the mechanism by which the repressor protein is removed, enabling the operon to turn on and facilitate the production of enzymes needed for lactose breakdown.

What is the primary difference between a repressible operon and an inducible operon?

• A repressible operon is always on, while an inducible operon is always off.

• A repressible operon is turned off by a repressor, while an inducible operon is turned on by an inducer.

• A repressible operon is activated by an inducer, while an inducible operon is deactivated by a repressor.

• A repressible operon is found in prokaryotes, while an inducible operon is found in eukaryotes.

What role does the lac operon play in E. coli?

• It helps E. coli to produce glucose.

• It allows E. coli to use lactose to generate ATP.

• It assists E. coli in breaking down starch.

• It enables E. coli to synthesize proteins.

Which sugar is used by E. coli to produce ATP when lactose is present?

• Glucose

• Sucrose

• Fructose

• Lactose

What happens to the repressor when lactose is present in the environment?

• The repressor changes its shape but remains attached.

• The repressor is degraded by enzymes.

• The repressor detaches from the operon, turning it on.

• The repressor binds more tightly to the operon.

How does the presence of lactose affect the transcription of genes in the lac operon?

• Lactose presence inhibits gene transcription.

• Lactose presence allows RNA polymerase to transcribe the genes.

• Lactose presence has no effect on gene transcription.

• Lactose presence causes the genes to be permanently turned off.

What is the function of RNA polymerase in the context of the lac operon?

• It transcribes the genes necessary for lactose breakdown.

• It degrades lactose in the cell.

• It binds to lactose to initiate transcription.

• It inhibits the repressor from binding to the operon.

What occurs when there is no lactose present in the environment?

• The repressor detaches from the operon.

• The operon is turned on and genes are transcribed.

• The repressor binds to the operon, turning it off.

• RNA polymerase transcribes the genes regardless.

What is the result of the repressor binding to the operon in the absence of lactose?

• The operon produces more repressor.

• The operon is deactivated.

• The operon synthesizes lactose.

• The operon is activated.