The walls of the tubes are essentially the outside surfaces of the cells. (sciencedaily.com)
The viruses also induce the bacteria to produce a second set of proteins that helps guide the assembly of P22 spheres, from the coat proteins, on the outer surface of the cell membrane. (sciencemag.org)
The outer surface of every cell of the body is a lipid or fat bilayer. (drjockers.com)