12 Biology by BISM Academy
2 – Mitotic apparatus
Formation of Mitotic Apparatus.
Centriole Separation.
At the beginning of the process in an animal cell, the partition of the centriole takes place, which have been duplicated during interphase but present in the same centrosome. Establishing Cell bipolarity Early in the mitosis the two pair of centrioles separate and migrate to opposite sides of the nucleus, establishing the bipolarity of the dividing cells.
Origination of Microtubules.
Three sets of microtubules (fibers) originate from each pair of centrioles. One set the astral microtubules, radiate outward and form aster, other two sets of microtubules compose the spindle.
Kinetochore microtubules attach to chromosomes at kinetochores and
Polar microtubules do not interact the chromosomes but instead interdigitate with polar microtubules from the opposite pole.
Composition.
These microtubules are composed of a protein tubulin and traces of RNA. This specialized microtubule structure including aster and spindle is called mitotic apparatus.
Function of Mitotic Apparatus.
This is larger than the nucleus, and is designed to attach and capture chromosomes, aligning them and finally separating them so that equal distribution of chromosomes is ensured.