Question

explain the action of lac operon when lactose sugar is not available.​

Answer 1

Explanation:

Glucose present, lactose absent: No transcription of the lac operon occurs. That's because the lac repressor remains bound to the operator and prevents transcription by RNA polymerase. Also, cAMP levels are low because glucose levels are high, so CAP is inactive and cannot bind DNA.

Answer 2

Lac operon is consist of  promoter, operator, lacZ, lac Y, lac A gene respectively

Explanation:

• Lactose operon is an inducible operon. lactose act as a inducer. The lac operon is expressed only in presence of lactose
• In presence of lactose, lactose molecule binds to the repressor and causes a conformational change in repressor so that it will not able to bind to the operator region.
• RNA polymerase bound to the promoter then moved in forward direction and perform transcription.
• In absence of lactose, repressor remain bound to the operator region. so the RNA polymerase that bound to the promoter region cannot move in forward direction, no transcription takes place.
• Lactose operon remain turned off.