Sejtmembránban

Sejtmembránban, 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 cell membrane is primarily composed of a phospholipid bilayer, which consists of two layers of phospholipid molecules. These molecules have a hydrophilic head and a hydrophobic tail. The hydrophilic heads face outwards and inwards, interacting with water, while the hydrophobic tails face each other in the interior of the membrane.

Embedded within or attached to this phospholipid bilayer are various proteins. These membrane proteins perform a wide range of functions, including acting as channels for the transport of ions and molecules, serving as receptors for signaling molecules, and participating in cell adhesion. Carbohydrates are also present, typically attached to proteins or lipids on the outer surface of the membrane, playing roles in cell recognition and interaction. The fluid mosaic model describes the cell membrane as a dynamic structure where components can move laterally within the plane of the membrane, giving it fluidity. This structure is essential for maintaining cell integrity, regulating internal conditions, and mediating communication between the cell and its surroundings.