Vesicle (biology and chemistry) In cell biology, a vesicle is a
small bubble within a cell, and thus a type of organelle.
Enclosed by lipid bilayer, vesicles can form naturally, for
example, during endocytosis. Alternatively, they may be prepared
artificially, when they are called liposomes. If there is only
one phospholipid bilayer, they are called unilamellar vesicles;
otherwise they are called multilamellar. The membrane enclosing
the vesicle is similar to that of the plasma membrane, and
vesicles can fuse with the plasma membrane to release their
contents outside of the cell. Vesicles can also fuse with other
organelles within the cell. Vesicles perform a variety of
functions. Because it is separated from the cytosol, the inside
of the vesicle can be made to be different from the cytosolic
environment. For this reason, vesicles are a basic tool used by
the cell for organizing cellular substances. Vesicles are
involved in metabolism, transport, buoyancy control, and enzyme
storage. They can also act as che