Sejtmembán

Sejtmembán is a Hungarian term that translates to "cell membrane." It refers to the biological membrane that surrounds the cytoplasm of a cell. The cell membrane is a selectively permeable barrier that controls the passage of substances into and out of the cell. It is composed primarily of a phospholipid bilayer, embedded with various proteins. These proteins play crucial roles in cell signaling, transport, and adhesion.

The phospholipid bilayer consists of two layers of phospholipid molecules. Each phospholipid molecule has a hydrophilic head and a hydrophobic tail. The hydrophilic heads face outwards towards the aqueous environment, while the hydrophobic tails face inwards, away from water. This arrangement forms a stable structure that separates the cell's internal environment from its external surroundings.

Proteins within the cell membrane can be integral, spanning the entire bilayer, or peripheral, attached to the surface. Integral proteins often function as channels or carriers for transporting specific molecules across the membrane. Peripheral proteins can be involved in signal transduction or maintaining the cell's shape. The fluid mosaic model describes the cell membrane as a dynamic structure where lipids and proteins can move laterally within the bilayer. This fluidity is essential for many cellular processes.