Question

How do hydrophobic and hydrophilic regions govern the arrangement of membrane lipids in a bilayer?

Answer 1

Hydrophobic regions repel water and in the phospholipid bilayer the legs of the phospholipid are hydrophobic and thus face inwards towards the other phospholipid. The hydrophilic heads are attracted towards water and thus are oriented outwards towards the fluid outside of the cell.

Answer 2

Lipids have a hydrophilic head and hydrophobic tail, that is, it is an amphipathic molecule. These characteristics allow lipids to be the appropriate molecules to make up cell membrane structures, as the hydrophilic head of the lipid faces the outside of the cell allowing the cell to come in contact with external substances, however, the hydrophobic lipid tail. faces the interior of the cell, preventing material from inside the cell from spilling out.