1.2.3 Phospholipids

Phospholipids are a type of lipid where one of the fatty acids in a triglyceride is replaced by a phosphate group. This substitution creates a unique molecule with both a hydrophilic (water-loving) head and hydrophobic (water-repelling) tails. As a result of this structure, phospholipids are polar molecules.

Phospholipid Structure:

• Hydrophilic Head: The phosphate group makes the head of the molecule attracted to water.
• Hydrophobic Tails: The fatty acid chains repel water and are non-polar.
• In water, this dual nature causes phospholipids to form structures called micelles, with the hydrophilic heads facing outwards towards the water and the hydrophobic tails tucked inside away from the water.

Phospholipid Structure Related to Their Properties:

• In an aqueous environment, phospholipids arrange themselves into a bilayer, which is the fundamental structure of cell membranes. This bilayer allows the cell to control what enters and exits, maintaining its internal environment.
• The hydrophilic heads of the phospholipids form the outer surface of the cell membrane, interacting with the watery environment both inside and outside the cell.
• Phospholipids can also form glycolipids by combining with carbohydrates. These glycolipids play an important role in cell recognition and signalling on the surface of cell membranes.