They would no longer require the synthesis of the enzyme beta-galactosidase
Operon
A transcription unit with a common promoter and regulatory genes controlling the expression of structural genes
Lac operon
Consists of one regulatory gene (i) and three structural genes (z, y, a)<|>The i gene codes for the repressor<|>The z gene codes for beta-galactosidase<|>The y gene codes for permease<|>The a gene encodes a transacetylase
Inducer
Lactose is the substrate for beta-galactosidase and regulates switching on and off of the lac operon
Regulation of lac operon
1. Repressor protein binds to the operator and prevents transcription
2. Inducer (lactose or allolactose) inactivates the repressor, allowing transcription
Glucose or galactose cannot act as inducers for the lac operon
Regulation of lac operon by repressor is referred to as negative regulation
