In
cell biology, an
organelle (ɔrɡəˈnɛl) is a specialized subunit within a
cell that has a specific function, and it is usually separately enclosed within its own
lipid bilayer.
The name
organelle comes from the idea that these structures are to cells what an
organ is to the
body (hence the name
organelle, the suffix
-elle being a
diminutive). Organelles are identified by
microscopy, and can also be purified by
cell fractionation. There are many types of organelles, particularly in
eukaryotic cells. While
Prokaryotes do not possess organelles
per se, some do contain protein-based microcompartments, which are thought to act as primitive organelles.