Question

Inducible operons______

A) are normally active.
B) are generally anabolic pathways.
C) are active in the presence of a repressor.
D) usually require a repressor to be transcribed.
E) usually require an activator to be transcribed.

Answer 1

Inducible operons like the lac operon are not active by default. They require an activator, which is usually the substrate that the operon's enzymes metabolize, such as lactose, to be transcribed.

Step-by-step explanation:

Inducible operons, such as the lac operon in E. coli, are typically not active but can be turned on in the presence of a specific inducer. For inducible operons, the correct answer is E) usually require an activator to be transcribed. This is because the repressor of an inducible operon is bound to the operator sequence under normal conditions, blocking transcription. When the substrate (such as lactose in the case of the lac operon) is present, it acts as an inducer by binding to the repressor and thereby preventing the repressor from binding to the operator.

Inducible operons are operons that are not normally active but can be activated under certain conditions. They are typically involved in catabolic pathways, where the genes are only required when a specific substrate is available. Inducible operons usually require an activator to be transcribed, which helps RNA polymerase bind to the promoter and initiate transcription.