Question

A mutation occurs in the trp operon DNA of E. coli and results in the change to the two UGG tryptophan codons in the 5′ UTR of the RNA to UAG stop codons. What effect will this mutation be expected to have on the regulation of this mutant trp operon compared to a wild-type operon?
A) In the presence of tryptophan, transcription of the structural genes will be reduced compared with a wild-type operon.
B) In the absence of tryptophan, transcription of the structural genes will be reduced compared with a wild-type operon.
C) In the presence of tryptophan, the repressor will bind to the operator/promoter region with the mutant operon more strongly than with a wild-type operon.
D) In the absence of tryptophan, RNA polymerase will not bind to the operator/promoter region with the mutant operon.
E) In the presence of tryptophan, transcription of the structural genes will be enhanced compared with a wild-type operon.

Answer 1

Answer:

E) In the presence of tryptophan, transcription of the structural genes will be enhanced compared with a wild-type operon.

Explanation:

A mutation can be described as any changes which occur in the DNA of an organism. Some mutations can be useful whereas others have devastating effects.

A stop codon is required to stop the transcription of a gene. If this code becomes mutated, then the process of transcription will continue to happen unless a new stop codon is recognized.

Hence, when tryptophan will be present, the mutations will cause more transcription of the structural genes.