Question

Which of the following statements describes prokaryotic transcription of the lac operon?

a) Inducible and regulated by a repressor
b) Constitutive and always active
c) Repressed by the presence of lactose
d) Inhibited by the absence of glucose

Answer 1

The lac operon is an inducible operon that is regulated by the presence of lactose and the absence of glucose. It is transcribed and translated into the necessary proteins for lactose metabolism when glucose levels are low and lactose is present.

Step-by-step explanation:

The lac operon is an inducible operon that is regulated by the presence of lactose and the absence of glucose. When glucose levels are low, the cAMP-CAP complex activates transcription of the lac operon, allowing it to be transcribed and translated into the necessary proteins for lactose metabolism. Additionally, when lactose is present, it acts as an inducer by binding to the repressor protein and preventing it from binding to the operator, thereby allowing transcription to occur. This regulation ensures that the lac operon is only active when glucose is limited and lactose is present.