Biology Reference
In-Depth Information
FIGURE 3.4
The structure of a single-layered phospholipid vesicle.
short: a more stable configuration is a closed, and therefore edgeless, surface such as
a vesicle (
Figure 3.4
).
The production of spherical vesicles, in which all parts are alike, is a common result of
mixing approximately cylindrical phospholipids with water but other geometries are also
possible. Closed cylinders, for example, are common and they are stable enough for measure-
ments to be made on their mechanical properties.
5
With the addition of divalent cations that
can promote association between membranes, helical morphologies are also possible.
6
Fila-
ments can also form, either when a hot isotropic solution of certain (but not all) lecithin deriv-
atives is slowly cooled,
7
or when water is added to a smear of lecithin dried on a microscope
slide. The formation of these filaments is a dynamic process; the structures shown in the still
micrograph in
Figure 3.5
, taken at the interface between a drop of water and a smear of
FIGURE 3.5
Bending and twisting tubes formed when water is added to a smear of dried lecithin on a micro-
scope slide.
