An F strain marked at 10 loci gives rise spontaneously to Hf

An F+ strain, marked at 10 loci, gives rise spontaneously to Hfr progeny whenever the F factor becomes incorporated into the chromosome of the F^+ strain. The F factor can integrate into the circular chromosome at many points, so that the resulting Hfr strains transfer the genetic markers in different orders. For any Hfr strain, the order of markers entering a recipient cell can be determined by interrupted mating experiments. From the following data for several Hfr strains derived from the same F^+ determine the order of markers in the F^+ strain.

Solution

Answer:

From the sequences provided in the table for the Hfr strains, the sequence of the markers are:

Z-H-E-R-S-K-O-W-I-T.

The circular map containing the order of the genes can be created with Z at the 12\'o clock position and placing the markers in the clockwise direction. The K marker will be at the 6\'o clock position.

Determination of the order of the markers:

Z-H-E-R (Forward)

O-K-S-R (Reverse order), i.e, R-S-K-O

K-O-W-I (Forward with overlap)

Z-T-I-W (Reverse-order), i.e, W-I-T-Z