Q. Four Hfr strains separately 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.

Demonstrate the location and orientation of the F factor in each Hfr strain.