Cytoskeletons

Cytoskeletons are the "bone and muscle" of the cell. There are three main types of cytoskeletons namely: microtubules, intermediate filaments, and microfilaments.

Microtubules are the skeletons of the cells. Generally, these are not attached to the membrane. Centrioles and spindle fibers are microtubules that play an important role during cell division. These microtubules help provide anchorage for organelles in the cell. They also act as tracks which the organelles, like ribosomes can move along in the cytoplasm. Locomotion of unicellular organisms like paramecium and euglena are made possible by the microtubules in the cilia and flagella, respectively. Cilia and flagella are the structures for locomotion that protrude from some cells. Cilia usually occur in large numbers on the cell surface. Flagella are usually limited to just one or a few per cell. The human sperm cell uses its flagella to swim.

Intermediate Filaments give support to the cytoplasm of cells. These are biochemically distinct from the microtubules, and microfilaments. Biological tests are done on the intermediate filaments to detect some disorders.

Microfilaments are the muscle of the cells. These are finger than microtubules and are generally attached to the membrane. Microfilaments give shape to the cell and are involved in the constriction of cytoplasm during mitosis.