Five Hfr strains A through E are derived from a single F+ strain of E. coli. The following chart shows the entry times in minutes of the first five markers into an F- strain when each Hfr strain is used in an interrupted-conjugation experiment:
A
B
C
D
E
mal+
1
ade+
13
pro+
3
pro+
10
his+
7
strS
11
his+
28
met+
29
gal+
16
gal+
17
ser+
16
gal+
38
xyl+
32
his+
26
pro+
23
ade+
36
pro+
44
mal+
37
ade+
41
met+
49
his+
51
met+
70
strS
47
ser+
61
xyl+
52
- Draw a map of the F+ strain, indicating the positions of all the genes and their distances apart in minutes. Show the insertion point and orientation of the F plasmid in each Hfr strain on your map.
- When using Hfr strain A, which gene would select to obtain the highest frequency of donor alleles in the Hfr exconjugants out of the following: xyl, mal, str, his?