A scientist created a new auxotrophic mutant of bacteria that is leu^- for a new Ames test.In order for the mutant to grow in the absence of leucine, a(n)_____ mutation would have to occur in the _____ gene.

Question

Quizplus · Accepted Answer

In order for the mutant to grow in the absence of leucine, a mutation in the leuS gene would have to occur. However, since the mutant already has a mutation in the leuS gene (leuS1), a second mutation in the same gene would not be able to restore the ability to grow without leucine. Therefore, the only option is an intragenic reversion in the leuU or leuP1 gene, which could restore the function of the leuS1 gene and allow the mutant to grow without leucine. Choice B, intragenic reversion, is the best answer.

A Scientist Created a New Auxotrophic Mutant of Bacteria That