Difference between microtubules, microfilament and intermediate filaments - This lecture
explains about the difference between microtubules, micro filaments and intermediate filaments.
Microfilaments are fine, thread-like protein fibers, 3-6 nm in diameter.
They are composed predominantly of a contractile protein called actin, which is the most abundant
cellular protein.
Microfilaments' association with the protein myosin is responsible for muscle contraction.
Microfilaments can also carry out cellular movements including gliding, contraction,
and cytokinesis.
Microtubules Microtubules are cylindrical tubes, 20-25
nm in diameter.
They are composed of subunits of the protein tubulin--these subunits are termed alpha and
beta.
Microtubules act as a scaffold to determine
cell shape, and provide a set of "tracks" for cell organelles and vesicles to move on.
Microtubules also form
the spindle fibers for separating chromosomes during mitosis.
When arranged in geometric patterns inside flagella and cilia, they are used for locomotion.
Intermediate Filaments
Intermediate filaments are about 10 nm diameter
and provide tensile strength
for the cell.
Examples
of the cytoskeleton in epithelial cells
In
the epithelial (skin) cells of the intestine, all three
types of fibers are present.
Microfilaments project into the villi, giving shape to the cell surface.
Microtubules grow
out
of the centrosome
to
the cell periphery.
Intermediate filaments connect adjacent cells through desmosomes.