In order to determine the overall chromosome map for e. coli, four hfr strains were obtained from a prototrophic streptomycin sensitive but erythromycin resistant (ermr) f+ ancestor. the start times of transfer during conjugation matings with strr f - strains carrying auxotrophic, fermentation, and erythromycin-sensitivity markers were determined for each hfr strain, as listed. a. (12 pts). using the times for transfer of each marker, draw a unified chromosome map of e. coli, showing the order and relative distances between these markers. b. (3 pts). place the origin of transfer (site of f insertion) on the map for hfr strains #2-4. c. (2 pts). what is the total length of the e. coli chromosome, in transfer minutes?