You have performed the following mating experiment using Hfr and F-strains of Escherichia coli: Hfr (thr⁺ leu⁺ gal⁺ strˢ) × F⁻ (thr⁻ leu⁻ gal⁻ strʳ). Which of the following selective media would you use to score recombinant colonies?
A) minimal medium
B) minimal medium + streptomycin
C) minimal medium + threonine
D) minimal medium + streptomycin + threonine

Question

Quizplus · Accepted Answer

The selective medium should allow only the growth of recombinant F- strains that have acquired the thr⁺, leu⁺, or gal⁺ genes from the Hfr strain while preventing the growth of the original Hfr strain. Streptomycin is used to kill the Hfr strain (strˢ), allowing only the strʳ F- recombinants to grow.

You Have Performed the Following Mating Experiment Using Hfr and F-Strains