Question

If the UGG codons in Region 1 of trpL were changed to AGG codons, what effect would this have on expression of the trp operon? If the UGG codons in Region 1 of trpL were changed to AGG codons, what effect would this have on expression of the trp operon? The operon would never be expressed. The operon would be constitutively expressed. The operon would be regulated by tryptophan, but attentuation would be triggered at higher levels of tryptophan than in wild type. The operon would be regulated by tryptophan, but attentuation would be triggered at lower levels of tryptophan than in wild type. The operon would be regulated by arginine levels; high levels of arginine would attenuate expression of trp genes.

Answer 1

The answer is;  C. The operon would be regulated by tryptophan, but attention would be triggered at higher levels of tryptophan than in wild-type.

The attenuator protein is a point of gene regulation in the translation process. Changing the codons would interfere with the bonding between region 1 and region 2 hence the hairpin structure (critical for stalling ribosomes) of the mRNA would be altered. Consequently,  attenuation of translation would be ineffective.  Regulation of the operon would, therefore, depend on the regulation of transcription, upstream.