Question

Assume that the gene trpA in an auxotrophic strain of E. coli is located at 27 minutes, whereas the gene pyrE is

located at 81 minutes.
Present an experimental scheme that would allow you to convert one of the auxotrophic strains to a prototrophic strain.
A) F+ (auxotroph) × F (wild type)
B) Hfr (auxotroph) × F (wild type)
C) F+ (wild type) × F (auxotroph)
D) Hfr (wild type) × F (auxotroph)
E) Hfr (auxotroph) × F (auxotroph)

Answer 1

The experimental scheme that would allow you to convert one of the auxotrophic strains to a prototrophic strain is option B) Hfr (auxotroph) x F (wild type). By mating an Hfr auxotroph strain with an F wild type strain, there is a possibility of transferring the trpA gene located at 27 minutes from the Hfr strain to the auxotroph strain.

Step-by-step explanation:

The experimental scheme that would allow you to convert one of the auxotrophic strains to a prototrophic strain is option B) Hfr (auxotroph) x F (wild type).

In Hfr (High Frequency of Recombination), the F plasmid is integrated into the bacterial chromosome, allowing for the transfer of chromosomal genes during conjugation. By mating an Hfr auxotroph strain with an F wild type strain, there is a possibility of transferring the trpA gene located at 27 minutes from the Hfr strain to the auxotroph strain. This would convert the auxotroph strain to a prototrophic strain, capable of synthesizing tryptophan.