Question: 3. A bacterial geneticist hopes to map genes a through g by means of interrupted mating experimen…

3. A bacterial geneticist hopes to map genes a through g by
means of interrupted mating experiments using three Hfr strains
designated X, Y, and Z. In all crosses the Hfr parent is
prototrophic for each gene and is streptomycin sensitive, whereas
the recipient F– strain is multiply auxotrophic and streptomycin
resistant.

a) How does an Hfr strain differ from an F+ strain? (2
points)

b) Why does it matter that the Hfr is streptomycin sensitive
while the F– strain is streptomycin resistant? (2 points)

c) From the data in the accompanying table, showing times of
entry in minutes, deduce the genetic map of the markers a through
g. Write the genes in correct order and between adjacent pairs of
genes write the distance in minutes. (6 points)