Microtubules
Microtubules are a component of the cytoskeleton in cells. They are made up of monomers of alpha and beta tubulin which dimerise to form a globular protein by the use of GTP hydroloysis. They are roughly 25 nm in diameter, the largest of all cytoskeletal proteins. Tubulin molecules then polymerize to form void cylinders of microtubules.Taxol stabalises the polymerized form of microtubules by binding to them. It is an important anticancer drug as it affects rapidly dividing cells such as tumour cells
Microtubules have multiple functions within a cell. The rigidity of microtubules allows them to maintain the cell's shape. They also control movement of the cell as well as movement of intracellular organelles [1]. Microtubules require organising centers in order to radiate throughout the cell such as centrosomes from which they form asters befre growing into mitotic spindles. During mitosis, microtubules form the mitotic spindle required to separate the chromosomes.
Microtubules are polar with a plus and minus end, they can assosiate with motor proteins such as kinesin or dyneins which are used to provide movement of cilium or flagellum in bacteria. Motor proteins hydrolyse ATP to drive movement and their tails can bind vesicles and organelles.
[2].
References:
Freeman. S, (2008) Biological Science 3rd edition