The Kinetochore is a multilayer protein structure that forms at the centromere region of each sister chromatid. The plus end of the microtubules forming mitotic spindles from the centrosomes bind to the kinetochore at specialised sites and form a bridge between the chromatids and the mitotic spindles in such a way that allows continual polymerisation and depolymerisation of the microtubule. This is key to the movement of chromatids during anaphase. During anaphase of mitosis the mitotic spindles contract to pull apart thesister chromatids. The kinetochore is essential for this movement as it binds to a microtubule motor protein that moves the sister chromatid to the minus end of the mitotic spindle at the poles of the cell. Free kinetochores with no microtubules bound act as a check point for mitosis, halting the process until all chromatids are bound, ensuring correct separation of chromatids and preventing aneuploidy.