Q22 of 29 Page 1

Given below is a schematic representation of lac operon:


(a) Identify i and p.


(b) Name the ‘inducer’ for this operon and explain its role.


(a) The i gene codes for the repressor of lac operon and p is the promoter.


(b) The inducer for lac operon is lactose. When lactose is present, the lac genes are expressed because allolactose binds to the Lac repressor protein and keeps it from binding to the lac operator. Allolactose is an isomer of lactose.


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