Plasma membrane

The plasma membrane of eukaryotes is a semi-permeable barrier that forms the boundary between the outside and the inside of the cell. It is similar to that of the prokaryotes, except that it contains sterols, flat molecules that give the membrane a greater rigidity and that stabilize the eukaryotic cell. There  are transport systems in the membrane that selectively import materials into  the cell, and  it is also involved in endocytosis and  exocytosis, where food  particles are  engulfed and  waste  products are expelled from  the  cell in membrane-bound vesicles. The plasma membrane is involved in key interactive processes between cells, like cell–cell recognition systems, as well as adhesion of the cell to solid surfaces.