Question

Describe what would happen in each of the following situations:

a. If a researcher moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene.

b. If a researcher moves the operator to the far end of the operon, past the transacetylase (lacA) gene

c.If a researcher moves the repressor gene (lacI), along with its promoter, to a position several thousand base pairs away from its normal position.

Answer 1

a) In lac operon the promoter function as a binding site of RNA polymerase for regulation of transcription. If promoter is moved into lacZ and lacY gene it would start transcription of lacY gene only. No transcription of lacZ gene i.e no production galactosidase enzyme and no metabolisn of lactose.  

b) Operator is a binding site of repressor and it also controls the structural gene of lac operon. If the operator is moved to the far end of operon, then operator can control the structural gene (lacZ, lacY , lacA) .

C) If the lacI gene with promoter is moved to away to normal position , it can not control the operator and then the structural genes are trancribed, no control of regulation of lacZ, lacY, lacA genes.