Conjugation:
* Mechanism: Direct contact between two bacterial cells. One cell, called the donor, possesses a conjugative plasmid, a circular DNA molecule that carries genes for conjugation. The plasmid replicates and a copy is transferred through a pilus (a protein tube) to the recipient cell.
* Transferred material: Primarily plasmids, but chromosomal DNA can also be transferred through a process called "Hfr conjugation".
* Example: The transfer of antibiotic resistance genes through the F-plasmid.
Sexduction:
* Mechanism: Involves a special type of F-plasmid called the F' plasmid. This plasmid integrates into the bacterial chromosome and then detaches, carrying a piece of chromosomal DNA along with it. The F' plasmid can then be transferred to a recipient cell through conjugation.
* Transferred material: A segment of chromosomal DNA along with the F' plasmid.
* Example: Transfer of the lac operon genes in *E. coli* through an F' plasmid.
Key differences:
| Feature | Conjugation | Sexduction |
|---|---|---|
| Mechanism | Direct contact via pilus | Conjugation followed by excision of F' plasmid |
| Transferred material | Plasmids, sometimes chromosomal DNA | F' plasmid with chromosomal DNA |
| Requirement | Conjugative plasmid in donor | F' plasmid in donor |
In summary:
* Conjugation is the transfer of genetic material directly between bacterial cells through a pilus.
* Sexduction is a specialized form of conjugation where a segment of chromosomal DNA is transferred along with an F' plasmid.
Both processes contribute to the spread of genetic diversity in bacterial populations, leading to adaptation to new environments and the emergence of antibiotic resistance.