In a mutant E coli strain CAP site of lac operon is mutated

In a mutant E. coli strain, CAP site of lac operon is mutated so the CAP protein can no longer bind. Will this mutation slow down culture growth in glucose-supplemented media? Y/N Will trip operon be responsive to tryptophan levels if trpL is deleted? Y/N Why attenuation can occur in bacteria but not in a eukaryotic cell? Under what conditions would trpR mutant E. coli strain synthesize tryptophan? constitutively never when tryptophan levels get so low that ribosomes pause at UGG codons

Solution

1. Yes, mutation slows down culture growth in glucose supplemented media.

Lactose is not a preferred carbohydrate source for E.coli. If lactose and glucose are present in the media, the cell uses all the glucose before lac Operon turns on.

As the concentration of glucose increases in the media, the amount of cAMP decreases. Hence results in the inactivation of the promoter, lac Oberon turns off.

2. Yes

The transcribed genes of the tarp operon is a sequence of at least 130 nucleotides called as trpL. The attenuation efficiency is correlated with the stability of a secondary structure embedded in trpL.

3. Because in eukaryotes, the mechanisms for terminating transcription appear to be different for RNA polymerase. Attenuation is a specialized mechanism utilized by bacteria to regulate untranscribed genes.

4. C.