a) Hydrophilic head

-phosphate group

-charged, polar

-forms H bonds with water

Role: Stabilize membrane

b) Hydrophobic tails

-fatty acid residues

-hydrocarbon chains are insoluble and non-polar

-repels water

-points inwards facing each other.

-In water, phospholipids self-assemble into bi-layer structure or micelle(if phospholipids are too few)

Roles: -Barrier to water-soluble substances.

-Allow passage to lipid soluble substances.

-Only lipid-soluble, small, uncharged molecules

can diffuse through the phospholipid bilayer

-ALSO: fatty acids help maintain fluidity of

membrane.

Learn: Cell Membrane Structure and Function