Final answer:
Phospholipids with long fatty acid tails aggregate due to their amphipathic nature, as the hydrophobic tails interact to minimize water exposure, leading to the formation of bilayers essential for cell membrane structure.
Step-by-step explanation:
Phospholipids with long fatty acid tails tend to aggregate together because they are amphipathic molecules, meaning they have both hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails. When placed in an aqueous environment, the hydrophilic heads of these phospholipids are oriented towards the water, while the long, hydrophobic tails are repelled by it. This leads to the aggregation of the tails, as they seek to minimize their exposure to water by interacting with one another through London dispersion forces and other hydrophobic interactions.
The length of the fatty acid chains affects the degree of interaction between the tails as well. Longer chains typically mean more hydrophobic interactions, increasing the tendency for these molecules to cluster together. This behavior is critical in the spontaneous formation of cellular structures like membranes, where phospholipids arrange themselves with tails facing inward, creating a bilayer that forms the basic structure of cell and organelle membranes. This orientation helps to protect the hydrophobic tails from water while exposing the hydrophilic heads to the aqueous environment, resulting in a lipid bilayer that is essential for many physiological functions.