Cilia and Flagella
Microtubules are responsible for the beating of the flagella and cilia.
Sperm of animals, algae, and some plants have flagella.
Unicellular eukaryotes are moved through the water by cilia or flagella
that act as a locomotor characteristic.
When cilia or flagella extend from cells that are held in place as part of a
tissue layer, they can move fluid over the surface of the tissue.
Motile cilia occur in large numbers on the cell surface.
There are only one or a few flagellas per cell.
Nonmotile cilias act as a signal receiving antenna for the cell.
Membrane proteins on nonmotile cilias transmit molecular signals from
the cell’s environment to its interior, triggering signalling pathways that
lead to changes in the cell’s activities.
A flagellum has a snakelike motion driving a cell in the same direction as
the axis of the flagellum.
Cilia have a back-and-forth motion.
Dyneins – large motor proteins that are made up of several polypeptides.
They are responsible for the bending movements of the organelle.
Microfilaments (Actin filaments)
They are also called actin filaments because they are built from molecules
of actin, a globular protein.
A microfilament is a twisted double chain of actin subunits.
Microfilaments are present in all eukaryotic cells.
The structural role of microfilaments in the cytoskeleton is to bear
Microfilaments in the plasma membran