Horizontal gene transfer

1: Donor bacteria 2: Bacteria who will receive the gene 3: The red portion represents the gene that will be transferred. Transformation in bacteria happens in a certain environment.
1: Donor bacteria cell (F+ cell) 2: Bacteria that receives the plasmid (F- cell) 3: Plasmid that will be moved to the other bacteria 4: Pilus. Conjugation in bacteria using a sex pilus; then the bacteria that received the plasmid can go give it to other bacteria as well.
Before it is transformed, a bacterium is susceptible to antibiotics. A plasmid can be inserted when the bacteria is under stress, and be incorporated into the bacterial DNA creating antibiotic resistance. When the plasmids are prepared they are inserted into the bacterial cell by either making pores in the plasma membrane with temperature extremes and chemical treatments, or making it semi permeable through the process of electrophoresis, in which electric currents create the holes in the membrane. After conditions return to normal the holes in the membrane close and the plasmids are trapped inside the bacteria where they become part of the genetic material and their genes are expressed by the bacteria.

There is evidence for historical horizontal transfer of the following genes: