how do chromosome motions occur?

Question

tyty

Answer 1

It has to do with a seldom-talked-about structure in every cell called the cytoskeleton.

The cytoskeleton is a network of protein chains that serve a variety of purposes in different cells, from providing a bit of shape to allowing them to move around. It is also critical in just about every process that requires something of a significant size to be in a particular location in the cell.

During cell division, structures called 'mitotic spindles' attach themselves to the cytoskeleton at either end of the cell, and then link themselves to a part of each chromosome called the centromere (the sort of knob in the middle of each X). Then, when they receive the proper signal, but spindles just reel in the fibers and draw all of the cromatids to one side or the other.

This is NOT a perfect process, however. If the cromosome doesn't break perfectly into two chromatids, or one of the spindles doesn't attach correctly, then one of the daughters will have too many or too few chromosomes. This is the largest (by far) cause of birth defects.

Follow the links below for very good images of the cytoskeleton (link 1) and the tubules of the spindles attaching to the centromeres (link 2). They're funny colours because these structures are all-but-invisible with just a light microscope.