Estimate order of genes on the hfr1 chromosome/ Biology
You have an F- strain of E. coli that is resistant to strepto- mycin (Str(r)) but requires the following amino acids for growth on minimal medium: arginine, cysteine, methionine, phenylala- nine, and proline. You do a series of interrupted mating exper- iments with two different Hfr strains, Hfr1 and Hfr2, both of which are wildtype for all amino acid markers, but are Lac(-) and Str(s) (sensitive to streptomycin).
The following data are the times in minutes at which you first observed recombinant progeny containing the indicated amino- acid marker (prototrophy).
Results of F- x Hfr1 cross Arg+ = 5
Cys+ = 65
Met+ = 75
Phe+ = 35
Pro+ = 10
Results of F- x Hfr2 cross Arg+ = 40
Cys+ = 70
Met+ = 60
Phe+ = 10
Pro+ = 35
Give the order of genes on the Hfr1 chromosome in the order transferred (e.g. CysPheMetArgPro)
Give the order of genes on the Hfr2 chromosome in the order transferred (e.g. CysPheMetArgPro)
You do a new mating experiment with the same strains. You interrupt the mating after 60 minutes and plate on a medium that selects for progeny that are re- combinant for the phenylalanine gene (Phe+). What sup- plements/antibiotics must be added to the minimal medium
