Hfr:a strain with F integrated into the chromosome that will give efficient transfer of some chromosomal markers. F+plasmid:1)Transfers itself at a frequency of 0.1 2)Does not transfer chromosomal markers Hfr 1)Transfers some chromosomal markers efficiently 2)Other markers transferred inefficiently -Gradient of transfer (It takes about 100 minutes to transfer the entire chromosome) Consider an F+integrating to make an Hfr: D A B D This process can be reversed to go back to the F+state: F+ B D The recombination can occur at a different position to give an F plasmid that carries a part of the chromosome.This form of F is called an F'. BHfr: a strain with F integrated into the chromosome that will give efficient transfer of some chromosomal markers. F+ plasmid: 1) Transfers itself at a frequency of 0.1 2) Does not transfer chromosomal markers Hfr 1) Transfers some chromosomal markers efficiently 2) Other markers transferred inefficiently - Gradient of transfer (It takes about 100 minutes to transfer the entire chromosome) Consider an F+ integrating to make an Hfr: A B C D B C D A This process can be reversed to go back to the F+ state: A B C D F+ The recombination can occur at a different position to give an F plasmid that carries a part of the chromosome. This form of F is called an F’. B C D B C A