One way of physically introducing DNA into cells is as carried by liposomes. Liposomes are lipid-bilayer bounded vesicles. They can be formed by hydrating lipids in aqueous solutions. If DNA is present in the solution, DNA becomes incorporated into the liposomes.
Liposomes interact with wall-less cells.
The liposomal contents are transferred to the inside of the cell. Both membrane fusion and endocytosis have been implicated as mechanisms. Genes present in the transferred DNA can be expressed transiently . The transferred DNA may also integrate into chromosomes and cell lines containing the integrated gene may be selected. The transfered genes will be in environments different from their normal environment and the positions of integration of the genes in different cell lines will differ.