Cell membrane
(Redirected from PM)
Definition
The cell membrane (also called the plasma membrane, cytoplasmic membrane, or plasmalemma, and abbreviated as PM) is a thin membrane completely surrounding the cell. It comprises a lipid bilayer. It controls the entry and exit of materials relative to the cell, and also the interaction and signals between the cell and its environment.
Summary
| Item | Value |
|---|---|
| Type of organisms whose cells contain cell membranes | All organisms; see all cells have cell membranes |
| Type of cells within the organisms that contain cell membranes | All cells; see all cells have cell membranes |
| Number of cell membranes per cell | 1; there's just one cell membrane enclosing the cell |
| Shape | The shape is the same as the shape of the cell. |
| Size | The cell membrane is about 5-10 nm (50-100 angstrom) thick. This is typical for lipid bilayers. |
| Location within cell | The cell membrane is the boundary of the cell, enclosing it from all sides. |
| Chemical constituents | Lipids, phospholipids, carbohydrates, proteins |
| Function | Control of the entry and exit of materials as well as signals from the environment to the cell |