HFR Cells and Gene Transfer Notes
HFR Cells and Gene Transfer
- The F plasmid can integrate into the host cell's genome.
- When this integration occurs, the host cell is termed HFR, which stands for high frequency of recombination.
- HFR cells can transfer some of their host genes to recipient cells.
Mechanism of Gene Transfer
- The sex pilus makes contact with the recipient F- cell, pulling the cells together.
- Donor chromosomes are transferred as single-stranded DNA, starting at the origin of transfer.
- Gene one, located closest to the origin of transfer, is transferred first.
- Segments of the integrated plasmid are at the beginning and end of the DNA being transferred.
Potential for Complete Genome Transfer
- It is theoretically possible for the entire genome and the F plasmid to be transferred to the recipient cell.
- However, this complete transfer does not occur because the donor and recipient cells separate before the process is finished.
Outcome of Gene Transfer
- The transferred single-stranded DNA becomes double-stranded in the recipient cell.
- Donor DNA integrates into the recipient cell's DNA via homologous recombination.
- The recipient cell acquires transferred genes but remains F-, while the donor cell remains HFR.
