Phospholipid bilayer

A phospholipid bilayer is the fundamental structure of cell membranes, composed of two layers of molecules called phospholipids. Each phospholipid has a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails. In the membrane, the heads face outward toward the watery environments inside and outside the cell, while the tails face inward, away from water, forming a double layer. This arrangement creates a semi-permeable barrier, controlling what enters and exits the cell, maintaining the cell's internal environment, and allowing communication and transport of substances crucial for cell function.