Bacterial Gene Transfer

3 Types of Gene Transfer in Bacteria:

1.Transformation. Which is the transfer of genes from Free DNA Molecules in the surrounding medium into a recipiant cell.

The main experiment linked to this was Griffiths work with smooth virilant (Deadly) strain of Pneumonia and rough (non-deadly) strain on Mice.
When the smooth strain was treated with heat it was killed and so when injected into the mouse it wasn't deadly.
However when the 'Heat-Killed' smooth strain and the rough (non-deadly) strain was mixed and injected together the mouse contracted pneumonia. This shows that the smooth strain has 'TRANSFORMED' the rough strain so it becomes deadly when they are mixed.

2.Conjugation. Transference of genes via direct cell to cell interactions.

This methods exchanged Plasmids (Very uncommon to transfer chromosomal DNA)

Bacteria of donor cell has a Pilus (protein hair like apendage) on its cell surface which attaches to the recipiant cell. The pilus pulls the recipiant call to the donor so that they can have direct transfer by temporarily joining membranes.
The donor cell unwinds it double stranded DNA plasmid and one of the strands are transfered from the donor to recipiant.
Both cells the split apart and synthesises () the complementory strand so that both donor and recipiant cells now have identicle plasmids.