The cytoskeleton in human cells forms the backbone of all cells found in eukaryotes. This cytoskeleton helps the cell to maintain its shape, helps to protect the cell, functions in intracellular transport and allows for the cell to move using either a flagella or cilia.
Three kinds of filaments make up the cytoskeleton. These include microfilaments, the filaments closest to the cell’s surface. Made up of linear pieces of actin, the subunits of the microfilament are pretty strong and flexible allowing for the changing shape of the cell, while making sure that the cell’s backbone is strong. The main responsibility of the microfilaments are to help maintain cell shape. One role these microfilaments play is in the process of cytokinesis, the final stage of cell division where two new daughter cells separate aided by microfilaments. These microfilaments or actin filaments as they are sometimes called are the thinnest of the filaments which help make up the backbone of the cell. Microtubules are the smallest filaments with a diameter of around six nanometers.
The second type of filaments, known as intermediate filaments are stronger filaments which like the actin filaments help to maintain cell shape. They were originally named intermediate filaments because their size was between that of the actin filaments and microtubules. This type of filament also helps to maintain the shape of the individual cell organelles, as well as the cell itself. Intermediate filaments are the second largest of the filaments with a diameter of around ten nanometers. While over seventy genes code for intermediate filaments, all of the filaments measure between nine and eleven nanometers.
The third type of filament in the cytoskeleton is the microtubules. These tubules play an important role with cilia and flagella and are therefore important in cell motion. These filaments can also function in producing force within the cell, but growing and shrinking. They are found in the dividing cell as an essential part of the mitotic spindle in cell division. Microtubules are the largest of the filaments in the cytoskeleton and are around twenty-three nanometers in diameter. In addition to their larger diameter these filaments can have a length of up to two hundred nanometers.
These are the main components of the eukaryotic cell cytoskeleton. While the cytoskeleton is considered the backbone of the cell, it is also part of the cytoplasm and is made up of protein. Found also in some prokaryotes, the cytoskeleton is essential to the life and function of all cells in an organism.