Harry Schwartz Eats the World

Phospholipid Bilayers

A cell’s membrane is mostly composed of phospholipids, tiny molecules shaped like double-tailed comets. The head of a phospholipid is hydrophilic (that is, it’s attracted to water) and the tails are hydrophobic.

In a cell membrane, phospholipids are arranged in double-wide sheets called bilayers. This allows the tails to hide inside the sheet, away from water.

So, here’s the neat part. If you dump a vial of phospholipids into a beaker of water and mix them up, the phospholipids will spontaneously form membranes! Little spheres called micelles are most common, but the phospholipids also form liposomes, which are basically simple cell membranes. I love when really simple rules give rise to complexity.

Practically speaking, this is how soap works! Soap is made out of fats (lipids) which surround particles of dirt in a micelle. The hydrophobic tails of the lipids attach to the dirt, and the hydrophilic heads are attracted to water, so the micelle can be rinsed away.

Hurray for science!

This entry was posted on Saturday, July 5th, 2008 at 7:58 am and is filed under science. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.