Cell membranes, also known as plasma membranes, are primarily composed of two major components: phospholipids and proteins.
Phospholipids are the fundamental building blocks of the membrane. Each phospholipid molecule has a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails. This unique structure allows phospholipids to arrange themselves in a bilayer, with their heads facing outward towards the water inside and outside the cell, while the tails face each other. This arrangement provides a barrier that controls the movement of substances in and out of the cell.
Proteins make up the second major component of cell membranes. These proteins are embedded within the phospholipid bilayer and serve various functions. Some proteins act as channels or transporters, facilitating the movement of ions and molecules across the membrane. Others serve as receptors, allowing the cell to respond to external signals. Proteins can also play a role in cell recognition and communication.
In summary, the two major components of cell membranes are phospholipids and proteins, both of which are essential for maintaining the integrity and functionality of cells.