What is an inducible operon?

An inducible operon is a genetic regulatory system that controls the expression of genes involved in catabolic pathways in response to a specific substrate. This system is found in some bacteria and functions to ensure that enzymes involved in degrading a specific nutrient are only produced when that nutrient is present.

In an inducible operon, the repressor protein binds to the operator region of the DNA, blocking the RNA polymerase from transcribing the genes. When the substrate (inducer) is present, it binds to the repressor, causing a conformational change that releases it from the operator region. The RNA polymerase can then transcribe the genes, leading to production of the enzymes needed for catabolism of the substrate.

The lac operon in E. coli is a well-known example of an inducible operon. It controls the expression of genes involved in lactose metabolism, and is induced by the presence of lactose in the cell. The lac operon is composed of three genes; lacZ, lacY, and lacA, which function together to cleave lactose into glucose and galactose. The lac operon is regulated by a repressor protein called LacI, which binds to the operator region of the DNA in the absence of lactose, and prevents transcription of the genes. When lactose enters the cell, it binds to the LacI repressor, causing a structural change that releases it from the DNA. The RNA polymerase can then access the promoter and transcribe the genes required for lactose metabolism.