Microtubule Types and Movement

There are three main types of microtubules, which perform different functions in the cell and occur during different phases in cell division. Aster microtubules extend from the spindle pole towards the cell cortex. Motor proteins attach themselves and exert an outward pulling force on the spindle poles to help position the poles correctly and pull the poles apart in anaphase B. The second type of microtubule is the kinetochore microtubule which connect the chromosome to the spindle pole and exerts a pulling force on the chromosome in anaphase A. The third type of microtubule is the interpolar microtubule, which overlaps microtubules in the center of the spindle. The proteins that bind here are important in stabilizing the spindle. These microtubules and their respective tasks are important to the phases of anaphase. Anaphase A involves the chromosomes being pulled poleward by the shortening of the kinetochore microtubules. Anaphase B involves the poles themselves as they are pushed and pulled apart. A sliding force is generated between interpolar microtubules to push the poles apart, while a pulling force acts directly on the poles to pull them apart.