noun, plural: microtubules
A microtubule is made up of polymers of alpha- and beta-tubulin dimers. It is a tubular structure with diameter of 25 nm, length ranging from 200 nm to 25 micrometers, and wall thickness of 5 nm. It exhibits polarity and are organized by a microtubule organizing centers (e.g. centrioles and basal bodies). Its functions are associated with providing intracellular shape, locomotion, and transport. For instance, in cellular division, the microtubules are a source of spindle fibers. They give rise to the spindle apparatus that plays an important role in moving and separating chromosomes. There are three main subgroups of microtubules: the polar microtubules, the astral microtubules, and the kinetochore microtubules. The polar microtubules are those that extend across the cell, i.e. from centrosome to centrosome. The astral microtubules are those that anchor the spindle poles to the cell membrane. The kinetochore microtubules are those that extend from the centrosome to the kinetochore protein in the centromere of the chromosome.
Word origin: Greek mīkrós (small)
- Microtubule organizing center
- Microtubule-associated protein
- Astral microtubule
- Microtubule nucleation
- microtubular (adjective, of or relating to microtubule)