Cell Cytoskeleton
provides structural support to the cell and determines its shape.
is a network of fibrillar proteins.
These fibrilar proteins are synthesized by polymerization of precursor molecules → if not needed anymore → disassemble → reassemble where and where needed → thus the cytoskeleton can be dynamic as needed.
Components:
Microtubules
Filaments
Thin filaments
Thick filaments
Intermediate filament
Microtubules
polymer of tubulin.
have a hollow lumen at the center.
20-30 nm in diameter.
Functions
Form and move structures like:
Cilia
Flagella
Centrioles
Mitotic spindle
Form a track for intracellular organelles to move from one area of the cell to the other
Thin & Thick Filaments
Thin filaments are made up of actin
Thick filaments are made up of myosin
Functions: They play role in...
Muscle contraction
Cell movement e.g. gliding, cytokinesis
Extend process from cell e.g.
Formation of axon in neuron
Formation of microvilli in epithelial cells
Intermediate Filaments
There is a large variety of subunit proteins that can form intermediate filaments.
Expression of different subunits in different cells results in formation of different intermediate filaments in different cells. For example:
Epithelial cells have keratins
Nerve cells have neurofilaments
Muscle cells have desmin
Functions
Radiate from the cell area subject to tensile stress → Reinforce such area against tensile stress.
In epithelial cells, they insert at the desmosomal junctions that attach neighboring cells to one another.