the relative rates of diffusion of these molecules from the fastest to the slowest is; Estrogen, propanol, alanine, sodium
Phospholipid bilayer consists of two layers of phospholipids, with a hydrophobic, or water hating, interior and a hydrophilic, or water loving, exterior. This bilayer gives the cell membrane a property to allow selective movement of molecules in and out of the cell. Ions and larger polar molecules cannot pass through the lipid bilayer, passing of the molecule through the membrane depends on its size and its electrical nature.
