Assume that the structural genes of the lac operon have been fused, through reco

Question

Assume that the structural genes of the lac operon have been fused, through recombinant DNA techniques, to the regulatory apparatus of the ara operon. If arabinose is provided in a minimal medium to E. coli carrying this gene fusion, would you expect -galactosidase to be produced at induced levels? Why?

-galactosidase would not be produced because arabinose inhibits transciption of the lac structural genes

-galactosidase would be produced because in the presence of arabinose, the lac structural genes would be transcribed.

-galactosidase would not be produced because lactose is necessary for transcription of the lac structural genes.

-galactosidase would be produced, as the absence of lactose induces transcription of the lac structural genes..

-galactosidase would not be produced because arabinose inhibits transciption of the lac structural genes

-galactosidase would be produced because in the presence of arabinose, the lac structural genes would be transcribed.

-galactosidase would not be produced because lactose is necessary for transcription of the lac structural genes.

-galactosidase would be produced, as the absence of lactose induces transcription of the lac structural genes..

Explanation / Answer

The most appropriate choice is option b, i.e. -galactosidase would be produced because in the presence of arabinose, the lac structural genes would be transcribed.

It is given that only the structural genes of lac operon have been fused to the regulatory apparatus of the ara operon. This means that the structural genes of the lac operon have been put under the control of the regulatory elements of the ara operon. Presence of arabinose turns on genes of the arabinose operon, so it will also turn on the expression of the structural genes of the lac operon, including -galactosidase.

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