In the absence of lactose, the lac repressor is

Which of the following names describes lactose?

The inducer of the lac operon is lactose.

Which of the following best describes the action of the lac repressor in the presence of an abundance of lactose? A. Allolaktose aktiveer die lac-repressor wat sy binding met die operator bevorder en sodoende transkripsie inhibeer / Allolactose activates the lac repressor promoting its binding with the operator, thus inhibiting transcription B. Allolaktose inaktiveer die lac-repressor wat sy binding met die operator bevorder en sodoende transkripsie bevorder / Allolactose inactivates the lac repressor promoting its binding with the operator, thus promoting transcription C. Allolaktose aktiveer die lac-repressor wat sy binding met die operator voorkom en sodoende transkripsie inhibeer / Allolactose activates the lac repressor preventing its binding with the operator, thus inhibiting transcription D. Allolaktose inaktiveer die lac-repressor wat sy binding met die operator voorkom en sodoende transkripsie bevorder / Allolactose inactivates the lac repressor preventing its binding with the operator, thus promoting transcription

Lactose catabolism in E coliGroup of answer choicesIs maximal when lactose is present in the environmentIs normally a constitutive functionIs essential since it is the only sugar the bacterium can use as an energy sourceProduces lactose for the cell’s useIs controlled by a repressible operon

The lac operon system, first described by Jacob and Monod, regulates lactose metabolism in . The is composed of a gene encoding a protein that normally keeps this operon in the position. Within the , the repressor binds to the , blocking transcription of structural genes needed for lactose metabolism. When is added to a cell's environment, it binds the repressor freeing the operator segment of the DNA. is now able to bind to the promoter, transcribing all three structural genes needed for lactose catabolism. When lactose again becomes depleted in the cell, the repressor binds to the operator blocking additional synthesis of enzymes from the .