Question

genetics

An E. Coli strain possesses the following genotype: F(P+)/" pCo+z+y+ where l' is a mutation that eliminates the production of repressor and PC eliminates the ability of the polymerase to bind the promoter. The structural genes will be transcribed both in the presence and absence of lactose O will be transcribed only if lactose is absent O will be transcribed only if lactose is present will not be transcribed under any onditions will be transcribed but not translated

Answer 1

Given that I- is a mutation that eliminates the production of the repressor, this means that the structural genes will be transcribed even if lactose is absent. The repressor binds to the operator and prevents the transcription of genes for lactose metabolism when lactose is absent. The repressor does not bind to the operator when lactose is present.

In the case of mutation where the repressor itself is absent, then the operon would work irrespective of the presence or absence of lactose. But, since there is another mutation (Pc) where the polymerase that transcribes the genes cannot bind to the promoter, there is simply no transcription of the genes. For transcription to occur, it is essential for the polymerase to bind to the promoter. And, without transcription, there is no translation of the genes either.

Therefore the right answer here is the fourth option, will not be transcribed under any conditions.

All other options would be wrong.