Phospholipid Bilayer

Real World Example

Imagine trying to keep a sandwich from getting soggy when you pack it for lunch. The way you might wrap the sandwich in a layer of wax paper and then a plastic bag is similar to how a cell uses a phospholipid bilayer to protect itself. Just as the wax paper and plastic bag create a barrier that keeps moisture out and freshness in, the double-layered sheet of phospholipids forms a selective barrier around the cell, controlling what enters and exits while maintaining the cell's internal environment.