Bacterial conjugation involves the transfer of genetic material between two bacterial cells through direct contact. It is mediated by specialized conjugative plasmids that contain genes for forming a pilus to connect the cells and for cutting and replicating the plasmid DNA to transfer it to the recipient cell. Well-studied conjugative plasmids are the F and R plasmids, and they contain genes like traJ that initiate the process of mating and formation of structures for genetic transfer.

1. Bacterial conjugation is the transfer of genetic
material between two bacterial cell via direct cell-
to-cell contact. Although often incorrectly
characterized as the bacterial equivalent of mating,
in fact it is simply the transfer of genetic material
from a donor cell to a recipient cell. Bacterial
conjugation is also known as a "type IV secretion
system".

2.  This behaviour is characterized by the presence of a
specialized plasmid (small, circular piece of transferrable
DNA most often found within bacteria) known as a
conjugative plasmid. The conjugative plasmid holds a
distinct and specialized set of coding regions including the
following :

3. OriT (Origin of Transfer): Unlike other plasmids, the
conjugative plasmid has its own origin of transfer nic
region.

4. This is a specialized portion of the genome where one of
the two strands of the circular plasmid DNA is cut to
allow for rolling circle replication of the plasmid
containing the OriT region into a recipient cell.

5. During rolling circle replication, the cut end of one
strand is inserted into thfge recipient cell while recipient
polymerases construct the complementary strand back
into a circular piece of DNA.

6. TraJ (Transfer genes): The activation of this gene sets off
a cascade of other plasmid genes (and thus
corresponding protein expressions) which act in concert
to form "mating" characteristics in the host bacterial
cell. Such salient characteristics include:
- growth of a pilus--a long whip-like apparatus used to
hook the two cells together
- fusion of the outer membranes to allow for transfer of
genetic material
- formation of "surface exclusion proteins" which
prevents the cell containing the conjugative plasmid
from mating with other conjugative plasmids of its type

7.  Two of the most well-studied and characterized types
of conjugative plasmids are types "F" (from the F
plasmid) and "R". The employed nomenclature for
conjugative plasmid genes is the gene name first with
the type afterwards. For example, the "TraJr" or "TraJR"
gene denotes the "TraJ" gene of the "R" type
conjugative plasmid.
 Note it was previously believed that transfer of genetic
material occurred via the pilus itself; now, most think
that the transfer of genetic material occurs via a
separate direct channel between the two cells.