Biology – Carbohydrates and lipids | e-Consult

Phospholipids are amphipathic molecules, meaning they possess both hydrophilic (water-loving) and hydrophobic (water-fearing) regions. The core structure consists of a glycerol molecule attached to two fatty acid tails and a phosphate group. The phosphate group is often further linked to a polar or charged molecule. This results in a molecule with a hydrophilic phosphate head and two hydrophobic fatty acid tails.

The fatty acid tails are long hydrocarbon chains, composed of carbon and hydrogen atoms. These are non-polar and repel water. The phosphate head, containing a phosphate group and often another polar group like choline or serine, is polar and readily interacts with water. This dual nature is key to their function.

The amphipathic nature of phospholipids drives the formation of biological membranes. In an aqueous environment, phospholipids spontaneously arrange themselves into lipid bilayers. The hydrophobic tails cluster together in the interior of the bilayer, shielded from water, while the hydrophilic heads face outwards, interacting with the aqueous environment both inside and outside the cell. This arrangement creates a barrier that separates the internal environment of the cell from the external environment, forming the basis of cellular membranes. The bilayer is fluid, allowing for lateral movement of phospholipids and proteins within the membrane.