Final answer:
Phospholipids are essential components of cell membranes, forming a bilayer that defines the cell's boundary and facilitates cell signaling and recognition.
Step-by-step explanation:
Phospholipids are critical components of cell membranes. These molecules are unique in that they have a hydrophilic 'head', consisting of a phosphate group and glycerol, and two hydrophobic 'tails' made of fatty acids. The ability of phospholipids to form a bilayer makes them essential for the structure and function of the plasma membrane. This bilayer forms a barrier that separates the cell from its external environment while allowing for the transport of necessary molecules.
In addition to forming the bilayer, phospholipids also play a role in cell recognition and signaling due to their interaction with other molecules like cholesterol, proteins, and carbohydrates.