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E. coli expresses a specific gene in the presence of lactose. The expression of this gene is under control by the lac operon, a sequence of nucleotides in the DNA which control the lac Operon al DNA ) laci CAP) (o) laczlacY
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Ans e: Lac I (regulatory gene) it is the monocistronic gene. it is a constitutively expressed gene. this regulatory gene is located close to the structural gene promoter and is said to be closely link to the structural gene.the expression of the regulatory gene produces monomeric polypeptides which undergo oligomerisation to produce the tetrameric repressor. the repressor is a helix turn helix protein having two alpha helical structures.

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