How are Hfr strains of bacteria different from F+ strains?

The key difference between F+ strains and Hfr is that F+ strains have F plasmids in the cytoplasm freely without integrating into bacterial chromosomes while Hfr strains have F plasmids integrated to their chromosomes.

Why is it called Hfr?

When the F factor is integrated into the bacterial chromosome, it can still act as the donor in a conjugation cross. These integrated strains are called Hfr, because of the high frequency of recombination that occurs when mated with F- bacteria.

How is an Hfr produced in bacteria?

Bacteria in which contains F-factor and a part of chromosomal DNA integrated in it is known as F-prime bacteria. F’ cells are formed from Hfr cell during induction of F- factor from chromosomal DNA in which F-factor carries a portion of chromosomal DNA along with it.

What does F+ F and Hfr mean?

Hfr (High frequency of recombination) Cells = Derivatives of F+ cells where F plasmid has integrated into host chromosomal DNA. This F plasmid is an episome which means it can either exist as an independent unit or it can integrate itself into chromosomal DNA.

Why is Hfr more efficient?

The high-frequency recombination strain of a bacterium. The sex element (F plasmid) is integrated into the bacterial chromosome resulting in about a thousand-fold more efficient transfer of the bacterial chromosome with the integrated F + element into the F− recipient cell.

What is the difference between F factor transfer and Hfr transfer?

In F factor conjugation, only the F factor is transferred to the F- strain; in HFr conjugation, the chromosomal DNA is transferred first, the F factor last.

How are Hfr strains formed?

Hfr’s can form by homologous recombination between an IS element on the F-plasmid and the same IS element on the host chromosome. Multiple IS insertions are present in many bacterial chromosomes.

What is the end result of Hfr bacterial conjugation?

If the Hfr cell loses the F-plasmid sequence, it reverts to a F–state. The end result of the conjugation process is similar to that obtained in sexual reproduction in eukaryotes (see below), namely the original F–cell now has a genome derived in part from itself and from the “donor” Hfr strain cell.

What is the end result of Hfr conjugation?

How could you get a Hfr strain?

A strain of bacterial that possesses the F factor integrated into the bacterial genome, hence, when it conjugates with another bacterium, it attempts to transfer a copy of the F factor as well as a portion of or the entire chromosome to the recipient bacterium.

Why is an Hfr strain?

What are Hfr in E coli?

High frequency of recombination. A strain of bacteria that has incorporated an F factor into its chromosome and can then transfer the chromosome during conjugation. In Escherichia coli, a cell having its fertility factor integrated into the bacterial chromosome; a donor (male) cell.