In the process of mitosis the two chromosome stands produced during S phase are separated from each other and packaged into the separated nuclei of the daughter cells. This process insures that each daughter cell will get one copy of each chromosome in an orderly and straightforward manner. You will learn moare about how this process occurs below.

In the early 1800's, when scientist first started to study the cell cycle, scientist could only observe plants using a microscope because they lacked the molecular and biochemical techniques we have today. They gave their greatest attention to mitosis or division when chromosomes are readily visible using the light microscope. They assumed because of little visible activity that the cell was resting between divisions and called this period interphase. We now know that interphase is a very active period at the molecular and metabolic level even though we can not see anything going on using the light microscope.