Nondisjunction is most likely responsible for the failure of a gamete to receive a copy of a particular chromosome.
What is non-disjunction?
When a pair of homologous chromosomes fails to segregate or separate at anaphase, both of the pair's chromosomes pass to the same daughter cell. This most likely happens during meiosis, but it can also happen during mitosis to create a mosaic individual. These are some potential causes of nondisjunction, while the exact cause or causes are unknown. Growing maternal age is linked to trisomy 21 and trisomy 18 fetuses and newborns, indicating that the mother's age may be a significant etiological component. Chromosomal structural defects such translocations and pericentric inversions might hinder chromosome pairing during meiosis and encourage nondisjunction.
Matthias Jacob Schleiden was a German botanist who, with Theodor Schwann, cofounded the cell theory. In 1838 Schleiden defined the cell as the basic unit of plant structure, and a year later Schwann defined the cell as the basic unit of animal structure.
