Permeability is the condition of being capable of having materials flow into and out of a membrane. the permeability of a cell membrane is determined by how easily a molecule can diffuse across the membrane. usually, only molecules that are fat-soluble can permeate across a cell membrane. why is this the case?

Permeability is the condition of being capable of having materials flow into and out of a membrane. The permeability of a cell membrane is determined by how easily a molecule can diffuse across the membrane. Usually, only molecules that are fat-soluble can permeate across a cell membrane. This is because the layer that is exposed on the linings of the cell membrane is nonpolar and can therefore allow the fat-soluble molecule to pass through.