Bacterial conjugation - Conjugation between F+ and F- cell

Bacterial conjugation is the unidirectional transfer of genetic material from a donor cell to a recipient by cell to cell contact or through conjugation tube. The process is first described by Lederberg, Hayes and Woolman in E.coli.

Sex in Bacteria?

The bacterium with F plasmid is the donor, F⁺ve or male. Fertility factor genes confer bacteria with the ability to transfer genetic material to the recipient cell. The bacterium without F factor is the recipient or F-ve strain or recipient.  In E.coli, both these strains are present, one with F factor, F⁺ve or male and other without F plasmid, F-ve or female.

Remember, in bacterial conjugation, F plasmids are generally transferred, not the entire bacterial genome.

Case I: Conjugation between F⁺ and F^- cell

Conjugation between F⁺ and F^- cell

Step 1: F⁺ cells produces hair like appendenges called sex pili which facilitates cell to cell contact with F^- strain by forming a conjugation tube. The formation of sex pili is governed by genes of F factor.

Step 2: Replication of F factor making a copy

Step 3: Transfer of copy of F plasmid to the recipient cell via conjugation tube.

Step 4: Conjugation tube dissolves

Now the F- strain is also F+. Remember, here bacterial genome is not involved.

In short:

F⁺ cell + F^- cell= F⁺ cell+ F⁺ cell
Case II: Conjugation between Hfr cell and F- cell

Case III: Sexduction or F-duction - Conjugation betweenF+cell and F- cell