Question

Using the blanks provided, put the steps of involved in mapping a bacterial chromosome by conjugation in chronological order using the numbers 1-6 in the blanks provided.

a. ___ ___ Cells that mated are checked for transfer of other genes from the Hfr to the F– strain.

b. ___ ___ At regular intervals, conjugation is interrupted by shearing the mating bacteria away from each other.

c. ___ ___ For each time point, cells that mated are selected—for instance, by requiring that a prototrophy or antibiotic resistance from each parent be present in one cell.

d. ___ ___ Select a donor Hfr strain and a recipient F– strain. The two strains must be different in genotype for several marker genes—for example, leu– and leu+, azir and azs.

e. ___ ___ The two strains are mixed together in a nutrient medium to allow conjugation to begin. After a few minutes, the culture is diluted to prevent new conjugations.

f. ___ ___ Order and distance of transferred genes are determined by comparing the time required for them to transfer from the Hfr to the F– strain.

Answer 1

The correct order is: d, e, b, c, a, and finally f

d. ___1___ Select a donor Hfr strain and a recipient F– strain. The two strains must be different in genotype for several marker genes—for example, leu– and leu+, azir and azs.

e. ___2___ The two strains are mixed together in a nutrient medium to allow conjugation to begin. After a few minutes, the culture is diluted to prevent new conjugations.

b. ___3___ At regular intervals, conjugation is interrupted by shearing the mating bacteria away from each other.

c. ___4___ For each time point, cells that mated are selected—for instance, by requiring that a prototrophy or antibiotic resistance from each parent be present in one cell.

a. ___5___ Cells that mated are checked for transfer of other genes from the Hfr to the F– strain.

f. ___6___ Order and distance of transferred genes are determined by comparing the time required for them to transfer from the Hfr to the F– strain.

Added in your image it would be: