The two chromatids of a metaphase chromosome represent replicated chromosomes, arranged at the equatorial plane of the cell, to be separated at anaphase. During metaphase, the kinetochore microtubules pull the sister chromatids back and forth until they align along the equator of the cell, called the equatorial plane. There is an important checkpoint in the middle of mitosis, called the metaphase checkpoint, during which the cell ensures that it is ready to divide.