On Shape Transformations and Shape Fluctuations of Cellular Compartments and Vesicles

We discuss the shape formation and shape transitions of simple
bilayer vesicles in context with their role in biology. In the
first part several classes of shape changes of vesicles of one
lipid component are described and it is shown that these can be
explained in terms of the bending energy concept in particular
augmented by the bilayer coupling hypothesis. In the second part
shape changes and vesicle fission of vesicles composed of membranes
of lipid mixtures are reported. These are explained in terms of
coupling between local curvature and phase separation.