DEFINITION/FUNCTION:a thin membrane (a double layer of lipids) enclosing the cytoplasm of a cell; proteins in the membrane control passage of ions (like sodium or potassium or calcium) in and out of the cell; "all cells have a cell membrane"

The cytoplasm plays a mechanical role, i.e. (example) to maintain the shape, the consistency of the cell and to provide suspension to the organelles.

They are found in both plant and animal cells.

external image cytoplasm.gif