Sketch a section of a phospholipid bilayer of a membrane, and label the hydrophilic head and hydrophobic tail of one of the phospholipids.

The hydrophobic tails are sandwiched in between because they are 'water-hating' leaving the hydrophilic ends (which are 'water-loving') to interact with the watery environment inside and outside of the cell. The hydrophobic ends are mainly made of fatty acid chains (and have no charges) while the hydrophilic ends are made of phosphate molecules that are negatively charged.