Cell membranes

Cell Membranes

Cell membranes (pronunciation: /sɛl ˈmɛmbreɪnz/), also known as the plasma membrane, is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells.

Etymology

The term "cell membrane" is derived from the Latin word 'cella' meaning a small room and the Greek word 'membrana' meaning a thin skin or film.

Structure

The cell membrane is composed of a lipid bilayer, including cholesterol that sits between phospholipids to maintain their fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that go across the membrane and peripheral proteins that sit just on the inside or outside of it.

Function

The primary function of the cell membrane is to protect the cell from its surroundings. It consists of the phospholipid bilayer with embedded proteins. Cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity and cell signalling and serve as the attachment surface for several extracellular structures, including the cell wall, the carbohydrate layer called the glycocalyx, and the intracellular cytoskeleton.

Related Terms

Lipid Bilayer: The basic structure of a biological membrane, composed of two layers of lipids.
Phospholipid: A type of lipid molecule that is the main component of the cell membrane.
Cholesterol: A lipid that forms an essential part of cell membranes and animal hormones.
Membrane Proteins: Proteins that interact with, or are part of, biological membranes.
Cell Wall: A structural layer surrounding some types of cells, situated outside the cell membrane.
Glycocalyx: A glycoprotein-polysaccharide covering that surrounds the cell membranes.
Cytoskeleton: A complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including bacteria and archaea.