Question

A gain of function mutation in the chaperone protein GroEL will actually force interactions between regions 3 and 4 of the tryptophan leader sequence mRNA. What would you expect to see in a cell with this particular GroEL mutation?

A.continued transcription of the trp operon even when tryptophan levels are high

B.transcription of the trp operon only when tryptophan levels are high

C.no transcription of the trp operon even when tryptophan levels are low

D.transcription of the trp operon only when glucose levels are low and tryptophan is present

Answer 1

Normally in the trp operon when the tryptophan levels are high in the cell, the 3 and 4 regions of the trp operon gets attenuated and the transcription of the genes doesnt take place. Only when trp levels are low, the 2 and 3 regions of the trp operon gets attenuated and the transcription of the genes takes place. So when the mutation in the GroEL causes the 3 and 4 regions to get attenuated, the transcription is terminated even when tryptophan levels are high or low.

Hence the correct answer to this question is: C. no transcription of the trp operon even when tryptophan levels are low.

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