Mitosis

So in the cell we currently in Metaphase, we have two sister chromatids 

Now we are in mitosis so the nuclear membrane around the chromatids starts to go away and the centrosomes migrate to opposite sides of the cell.

 Inside the Centrosomes there are two Centrioles which are two cylinders. They are all connected via microtubules which are sort of strings connecting everything together, the spindle fibres (microtubules) bind to the kinetochores of chromosomes, NOT the centromeres.

The microtubules pull and push the sister Chromatids around the cell. And they will rip the Chromatids in half and pull each half to each side of the cell. After they are split in half they are called kinetochores and this phase is called Anaphase.

The last phase is called Telophase and then the one cell will split into two and the cycle repeats it self again.