cytoplasmamembránt

The cytoplasmamembran, also known as the cell membrane or plasma membrane, is a biological membrane that separates the interior of all cells from the outside environment. It is a selectively permeable barrier that controls the passage of substances into and out of the cell. The membrane is composed of a phospholipid bilayer with embedded proteins. Phospholipids are amphipathic molecules, meaning they have both a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail. This arrangement causes them to form a bilayer in aqueous environments, with the hydrophobic tails facing inward and the hydrophilic heads facing outward.

Proteins within the membrane play various roles, including transport of molecules, signal transduction, and cell recognition. Some proteins span the entire membrane, acting as channels or carriers for specific substances. Others are peripheral, attached to the surface of the membrane. The fluid mosaic model describes the structure of the cell membrane, suggesting that the phospholipids and proteins are able to move laterally within the membrane, giving it a fluid character. This fluidity is essential for many cellular processes, such as cell division and membrane fusion. The cytoplasmamembran also plays a role in maintaining cell shape and integrity, and in interacting with the extracellular matrix. It is a dynamic structure that is constantly being remodeled and repaired.