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Cytoskeleton Tutorial

Internal cell movement

The cytoskeleton acts as a "track" on which cells can move organelles, chromosomes and other things. Some examples are:
  1. Vesicle movement between organelles and the cell surface, frequently studied in the squid axon.
  2. Cytoplasmic streaming
  3. Movement of pigment vesicles for protective coloration
  4. Discharge of vesicle content for water regulation in protozoa
  5. Cell division--cytokinesis
  6. Movement of chromosomes during mitosis and meiosis
Cellular motors
Cells have protein motors that bind two molecules, and using ATP as energy, cause one molecule to shift in relationship to the other. Two types of these protein motors are myosin and actin, and dynein or kinesin and microtubules. These families of proteins all have a motor end, but may have several kinds of different molecular structures on the binding end. When these proteins bind, they can cause many different molecules, organelles, etc. to move.
To the right is an example of the different binding ends found in the kinesin family of motors. Family of kinesin motors
When linked to other microtubules, protein motors can cause motion if the ends are fixed or extend the lengths of the fiber bundles if the ends are free.

Protein motors can cause motion

Broken motors
In healthy individuals, the protein dystrophin is part of the linkage between the cellular cytoskeleton and the adhesive proteins on the outside of the cell. In Duchenne Muscular Dystrophy, however, the gene that codes for dystrophin is defective, resulting in muscle degeneration and finally death. This disease is X-linked recessive and occurs in 1 out of every 3,500 males.

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