F plasmid of high frequency recombination is

Hfr Conjugation: F factor being a plasmid, is always Extra-chromosomal It may integrate with bacterial chromosome and behave as episome. Such donor cells are able to transfer chromosomal DNA to recipient cells with high frequency in comparison to F+ cells, therefore, named as Hfr cells (high frequency of recombination). During conjugation of Hfr cell with an F- cell, only few chromosomal genes along with only a pa of the F factor get transferred. Hence, F- recipient cells do not become F+ cells.