The plasma membrane, also known as the cell membrane, is a phospholipid bilayer that surrounds the cell and separates its internal environment from the external environment. It is a selectively permeable barrier that regulates the passage of molecules in and out of the cell. The plasma membrane also plays a crucial role in cell signaling, cell adhesion, and maintaining cell shape. It is composed of lipids, proteins, and carbohydrates, and is essential for the survival of all cells.
