How does the geometry of polar lipids define formation of micelles, vesicles and membrane bilayer?

Micelles: Forms in the solution of amphipathic molecules that have larger head than tail Aggregation occurs when the concentration of molecules is higher than a certain threshold Individual units are wedge-shaped (cross section of head greater than that of side chain) Vesicles: Small bilayers will spontaneously seal into spherical vesicles Vesicles fuse readily with cell membranes or with each other. Membrane bilayer: consists of two leaflets of lipid monolayers Individual units are cylindrical (cross section of head equals that of side chain) One leaflet faces the cytoplasm Another leaflet faces the extracellular space or the inside of membrane- enclosed organelle