Biology Reference
In-Depth Information
WATER
AIR
AIR
WATER
Lipid Bilayer
Soap Bubble
FIGURE 9.3
The lipid bilayer compared to a soap bubble. Both are made from amphipathic molecules, only
their orientation is reversed.
light
source
BLM
APPARATUS
telescope
hole
gray
colored
black
FIGURE 9.4
Apparatus for making the original BLM (top). Appropriate polar lipids are dissolved in an organic
solvent and added across a small aperture in a Teflon cup (bottom). The aperture is observed using a small telescope
by 90
reflected light. Initially the lipid solution appears gray. As the membrane thins, partial destructive inter-
ference of the reflected light makes the developing membrane appear multi-colored. Eventually a black spot
appears in the thick, colored membrane identifying a small area that has become bimolecular. The spot rapidly fills
almost the entire aperture indicating the entire membrane has become a lipid bilayer. Various membrane electrical
properties can be measured using electrodes on either side of the aperture.
