Question

1) Choose from the following options to complete the passage below: F-, F+, F', Hfr.

A(n) ___?___ cell, which has the F plasmid incorporated into the bacterial genome, can only conjugate with ___?____

cells. If the plasmid recircularizes, carrying some of the bacterial DNA with it, the cell is now considered to be ___?____.

2) If conjugation occurs between the two cells below, what will be the genotype of the exconjugant cell?

Donor Recipient lac+ lac-

a) F+ lac+

b) F+ lac-

c) F- lac+

d) F- lac-

Thank you so much for your help!

Answer 1

1)

A F⁺ cell contains F plasmid incorporated into bacterial genome can only conjugate with F^- cell to donate the plasmid. The plasmid recircularizes carrying bacterial DNA with in it is called HFR (high frequency recombinant) cell.

2) Conjugation is a process of genetic exchange between F⁺ and F^- cells. The F⁺ cell is a donor and F^- cell is a recepient that receives plasmid. Conjugation between F⁺ lac⁺ and F^- lac^- results in F⁺ cell donating a copy of F plasmid to F^- cell. Therefore genotype of exconjugant cell would also be F⁺ lac^- . Option b is correct.