The cytoskeleton is an important network of protein filaments within the cytoplasm of the cell. It provides a structural framework for the cell. It helps with cell movement and the movement of cytoplasmic components during several processes such as endocytosis, phagocytosis and exocytosis.
There are three main components, the microfilaments, microtubules and intermediate filaments.
The microfilaments are made of actin polymers which are components in muscle too. The structure of these microfilaments is two intertwined strands of the actin polymer. The main function of these microfilaments is to maintain cell shape by resisting tensions which means these cells remain together without being crushed or being pulled apart.
The Intermediate Filaments
Intermediate filaments are composed of many different types of proteins such as keratin, lamin and vimentin. Structurally, they are turned into a fibres which are wound into something like thick cables. As well as maintaining cell shape as microfilaments do, they also provide anchors for the organelles and the nucleus, fixing their position in the cell.
Microtubules are unique in that they are made of two alpha-tubulin and beta-tubulin proteins. As a structure they form a hollow tube of tubulin dimers. Their function is specifically to maintain cell shape by also providing a tension so that compression is resisted. They push the cell outward which prevents them being crushed. They also allow for the movement of chromosomes during cell division and also help keep organelles in position. They are also a component in flagella.