can observe how lipids organize themselves. Have you
ever seen cold soup with a film of fat on top? Or do this:
shake up a bottle of water that has some oil in it. If
you let the water stand undisturbed for a few hours, you will
see the oil rise to the top and form a film all by itself.
Using vessels like those shown
on the right, we can collect oil separate from water by draining
off the lower liquid compartment. Membrane lipids can be
extracted by homogenizing tissue in water and letting the
lipid separate. More efficient is to use an organic solvent,
like hexane (see toxic hazards in protein unit). Such
solvents can produce purer separations of oil from water.