Lipid Bilayers vs Micelles

[seabreeze]

Hey guys,

First time posting on this board, and just had a question regarding membrane formation. Why is it that things like phosphlipids and glycosphingolipids (like sphingomyelin and glycosphingolipids) form lipid bilayers when theyre exposed to water, whereas some things form micelles instead? i know that the structure of these is rectangular, but what exactly causes them to form the linear side-by-side bilayers, instead of just curling up circularly like a micelle? They both seem to interact similarly with water too (expose hydrophilic polar heads but hide their hydrophobic tailes on the inside). My notes don't do a very good job of explaining this, so any sort of insight would be greatly appreciated. Thanks!

[BioLad]

A bit of a blurb here: http://en.wikipedia.org/wiki/Micelle that talks about their formation.
Sadly I'm not that interested in micelles or I could give you a better explanation.

[n0vad3m0n]

I don't know what a micelle is (we haven't covered that in class) but we did go over properties of phospholipids.

A phospholipid with two hydrophobic tails will prevent the lipid in forming a circular fashion. These water-fearing tails will effectively orient the adjacent phospholipids into a bilayer position.