Genetics question:
Four Hfr strains independently derived from a wild type but Str^S (to the power of S) prototrophic E. coli strain were crossed to a multiple auxotrophic Str^R F^- strain that is deficient in synthesis of arginine (arg), cysteine (cys), guanine (gua), histidine (his), lysine (lys), methionine (met), proline (pro), thymine (thy), and uracil (ura).
The time-of-entry mapping method was used to determine the first five markers transferred from each Hfr during a synchronized conjugation experiment. The markers and their transfer order form each Hfr are shown below.
A lys - arg - ura - cys - thy
B his - pro - gua - thy - cys
C ura - arg - lys met - his
D thy - gua - pro - his - met
Place all markers in order on a single circular genetic map.
Show the location and orientation of the F factor in each Hfr strain.