Rasvakalvojen

Rasvakalvojen, also known as the lipid bilayer, is a fundamental structure in cell biology. It forms the basis of all cell membranes and is composed primarily of phospholipid molecules. Each phospholipid has a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails. In an aqueous environment, these molecules spontaneously arrange themselves into a bilayer, with the hydrophobic tails facing inward, away from water, and the hydrophilic heads facing outward, towards the intracellular and extracellular fluids.

This arrangement creates a stable barrier that separates the internal environment of the cell from its external surroundings. The lipid bilayer is not rigid; it is a fluid structure where the phospholipids and embedded proteins can move laterally. This fluidity is crucial for many cellular processes. Embedded within and attached to the lipid bilayer are various proteins, which perform a wide range of functions. These include acting as channels and transporters for molecules to cross the membrane, serving as receptors for signaling molecules, and participating in cell adhesion. The composition of the lipid bilayer, including the types of phospholipids and the presence of cholesterol, can vary between different cell types and organelles, influencing membrane fluidity and function.