DNA Transformation Notes
- DNA transformation involves the transfer of naked DNA into a recipient cell.
- Initial Binding: Double-stranded donor DNA binds to specific receptors on the surface of a competent cell.
- DNA Degradation and Entry: One strand of the donor DNA is degraded by nucleases.
- The remaining single-stranded donor DNA enters the cell.
- Homologous Recombination: The single-stranded donor DNA pairs with a homologous region on the recipient DNA.
- Integrated into the recipient genome through a breakage and reunion mechanism called homologous recombination.
- Mismatch Repair: If there are differences between the nucleotide sequences of the donor and recipient DNAs, the mismatch repair system is activated.
- The repair system removes either the donor or the recipient strand.
- Replaces it with the complementary sequence.
- Since either strand may be repaired, some cells contain the new donor DNA, and others have the original DNA sequences.
- Selection of Transformants: In the laboratory, cells are plated on selective media, allowing only the transformants to grow.
Homologous Recombination
- A breakage and reunion mechanism.
Mismatch Repair System
- Activated when there are differences between the nucleotide sequences of the donor and recipient DNAs.
- Either the donor or the recipient strand is removed and replaced with the complementary sequence.
- The outcome is that some cells contain the new donor DNA, and others have the original DNA sequences.
- Cells are plated on selective media.
- Only the transformants (cells that have successfully incorporated the donor DNA) will grow.