Chapter 6, Problem 18P

An interrupted mating study is carried out on Hfr strains $\text{1, 2, and 3}$ identified in the problem above. After conjugation is established, a small sample of the mixture is collected every minute for $\text{20}$ minutes to determine the distance between genes on the chromosome. Results for each of the three Hfr strains are shown below. The total duration of conjugation (in minutes) is given for each transferred gene.

a. For each Hfr strain, draw a time-of-entry profile like the one in Figure $\text{6}\text{.8}$ a.

b. Using the chromosome map you prepared in answer to Problem $\text{15}$, determine the distance in minutes between each gene on the map.

c. Explain why azi is the last gene of strain $\text{2}$ to transfer in the $\text{20}$ minutes of conjugation time. How many minutes of conjugation time would be needed to allow the next gene on the map to transfer from Hfrstrain $\text{2}$?

d. Write out the interrupted mating results you would expect after $\text{20}$ minutes of conjugation for Hfr strains $\text{4}$ and $\text{5}$. Use the format shown at the beginning of this problem.

e. In minutes, what is the total length of the chromosome in the donor species?