Q. A cross is finished between 2 E. coli strains: Hfr arg+ bio+ leu+ (x) F- arg- bio- leu-. Interuppted mating studies explain that arg+ enteres the recipient last, so arg+ recombinants are selected on a medium containing bio and leu only. The recombinants are tested for the presence of bio+ and leu+. The following numbers of individuals are found for each genotype:
arg+ bio+ leu+ 320
arg+ bio+ leu- 8
arg+ bio- leu+ 0
arg+ bio- leu- 48
What is the gene order? What are map distances in recombination units?