technique used to look at membranes that reveal the pattern
of integral membrane proteins.
General outline of technique:
1. Cells are quickly frozen in liquid nitrogen (196C),
which immobilizes cell components instantly.
2. Block of frozen cells is fractured. This fracture is
irregular and occures along lines of weakness like the
plasma membrane or surfaces of organelles.
3. Surface ice is removed by a vacuum (freeze etching)
4. A thin layer of carbon is evaporated vertically onto
the surface to produce a carbon replica.
5. Surface is shadowed with a platinum vapor.
6. Organic material is digested away by acid, leaving
7. Carbon-metal replica is put on a grid and examined
by a transmission electron microscope.