Definitions for "Nondisjunction"
Failure of homologous chromosomes (at meiosis) or sister chromatids (at mitosis) to segregate properly, resulting in unequal distribution to daughter cells. A commonly error leading to chromosomal disease.
an error that occurs during the division of sex chromosomes, causing either too much or too little genetic information to be placed in an egg or sperm when it is formed
failure to separate chromatids of a given chromosome during cell division. In mitosis the centromere is not broken during anaphase resulting in both chromatids going to the same daughter cell. In meiosis one of two events may occur: 1) synapsed homologous chromosomes (tetrads) fail to separate during anaphase I; 2) failure to break the centromere of a chromatid pair (diad) during anaphase II resulting in both chromatids going to the same daughter cell.