Cytoskeleton Anatomy

Fibroblast Cell
This fibroblast cell has been stained to reveal its structures: nucleus purple and cytoskeleton yellow. Fibroblasts are found in connective tissue. DR GOPAL MURTI/Science Photo Library/Getty Images

The cytoskeleton is a network of fibers that forms the "infrastructure" of eukaryotic cells, prokaryotic cells, and archaeans. In eukaryotic cells, these fibers consist of a complex mesh of protein filaments and motor proteins that aid in cell movement and stabilize the cell.

Cytoskeleton Function

The cytoskeleton extends throughout the cell's cytoplasm and provides a number of important functions.

  • It helps the cell maintain its shape and gives support to the cell.
  • A variety of cellular organelles are held in place by the cytoskeleton.
  • It assists in the formation of vacuoles.
  • The cytoskeleton is not a static structure, but is able to disassemble and reassemble its parts in order to enable internal and overall cell mobility. Types of intracellular movement supported by the cytoskeleton include transportation of vesicles into and out of a cell, chromosome manipulation during mitosis and meiosis, and organelle migration. The cytoskeleton makes cell migration possible as cell motility is needed for tissue construction and repair, cytokinesis (division of the cytoplasm) in the formation of daughter cells, and in immune cell responses to germs.
  • The cytoskeleton assists in the transportation of communication signals between cells.
  • It forms cellular appendage-like protrusions, such as cili and flagella, in some cells.

Cytoskeleton Structure

The cytoskeleton is composed of at least three different types of fibers: microtubules, microfilaments, and intermediate filaments.

These fibers are distinguished by their size with microtubules being the thickest and microfilaments being the thinnest.

Protein Fibers

  • Microtubules are hollow rods functioning primarily to help support and shape the cell and as "routes" along which organelles can move. Microtubules are typically found in all eukaryotic cells. They vary in length and measure about 25 nm (nanometers) in diameter.
  • Microfilaments or actin filaments are thin, solid rods that are active in muscle contraction. Microfilaments are particularly prevalent in muscle cells. Similar to microtubules, they are typically found in all eukaryotic cells. Microfilaments are composed primarily of the contractile protein actin and measure up to 8 nm in diameter.
  • Intermediate filaments can be abundant in many cells and provide support for microfilaments and microtubules by holding them in place. These filaments form keratins found in epithelial cells and neurofilaments in neurons. They measure 10 nm in diameter.

Motor Proteins

A number of motor proteins are found in the cytoskeleton. As their name suggests, these proteins actively move cytoskeleton fibers. As a result, molecules and organelles are transported around the cell. Motor proteins are powered by ATP, which is generated through cellular respiration. There are three types of motor proteins involved in cell movement.

  • Kinesins move along microtubules carrying cellular components along the way. They are typically used to pull organelles toward the cell membrane.
  • Dyneins are similar to kinesins and are used to pull cellular components inward toward the nucleus. Dyneins also work to slide microtubules relative to one another as observed in the movement of cilia and flagella.
  • Myosins interact with actin in order to perform muscle contractions. They are also involved in cytokinesis, endocytosis (endo-cyt-osis), and exocytosis (exo-cyt-osis).

Journey into the Cell

The following organelles and structures can also be found in eukaryotic cells:

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    Your Citation
    Bailey, Regina. "Cytoskeleton Anatomy." ThoughtCo, Sep. 14, 2016, Bailey, Regina. (2016, September 14). Cytoskeleton Anatomy. Retrieved from Bailey, Regina. "Cytoskeleton Anatomy." ThoughtCo. (accessed November 24, 2017).