Final answer:
The F plasmid uses the bacterial chromosome's origin of replication to replicate when it integrates into the chromosome. This creates an Hfr cell, which can participate in conjugation and share genetic material with F- cells through a sex pilus.
Step-by-step explanation:
When the F plasmid integrates into the bacterial chromosome, it uses the bacterial chromosome's origin of replication to replicate. This integration event transforms the bacteria into what is known as a high-frequency recombination (Hfr) cell. In this state, the F plasmid becomes part of the chromosomal DNA, and during cell division, the combined DNA of plasmid and chromosome is replicated as a single unit.
The origin of replication in prokaryotes is typically a single point on their circular chromosome. When the F plasmid integrates, it becomes subject to the same replication mechanisms as the host chromosome. If excision of the F plasmid from the chromosome occurs imprecisely, it may result in an F' plasmid that contains some chromosomal genes, which can then be transferred to another bacterium through conjugation.
During conjugation, a special pilus known as the F pilus or sex pilus formed by the donor cell (Hfr cell) extends and makes contact with the recipient (F- cell). This establishes a bridge between the two cells, allowing for the transfer of genetic material. In the case of an Hfr cell, a portion of the chromosomal DNA, initiated at the origin of replication, and any integrated F sequence is transferred to the F- recipient.