The normal separation or moving apart of chromosomes toward opposite poles of the cell during cell division.
Disjunction normally occurs during the anaphase of mitosis and meiosis (I and II).
During the anaphase of mitosis, sister chromatids separate and move towards opposite poles of the cell.
In meiosis, disjunction happens when homologous chromosomes move apart toward the opposite poles of the cell in anaphase I. Disjunction again occurs when sister chromatids separate and move away from each other during anaphase II.
Related term: disjunction mutant.
See also: anaphase.