What causes tetraploidy?
There are multiple exceedingly rare potential theoretical causes of tetraploidy that all have to do with failure of formation of egg or sperm cells, failure of normal cell division, or failure of normal fertilization. During the formation of eggs and sperm, chromosome pairs usually separate so that each sperm or egg cell contains only one copy of each of the 23 pairs of chromosomes typically present in the cells of a body. Sometimes errors occur during this process of chromosome separation which result in the egg or sperm receiving extra chromosomes. These errors in the separation of chromosomes are called nondisjunction.
One potential cause of tetraploidy is errors in chromosome division occurring in both the sperm and the egg resulting in each sperm and egg having 46 chromosomes, instead of the typical 23. In this situation, when the sperm fertilized the egg, the resultant cells would have four complete sets of chromosomes, or 92 chromosomes.
Another possible genetic mechanism that would result in tetraploidy is a normal egg and sperm cell resulting in a normal conception with 46 chromosomes, but failure of that first cell formed by the egg and sperm cells to divide properly, and the resulting product being a cell with 92, instead of 46, chromosomes.
Finally, there is a possible error in chromosome division and fertilization that might result in tetraploidy. If there was an error in the formation of an egg cell and the egg cell had 46 chromosomes instead of the typical 23, and then that egg cell was fertilized by two normal sperm instead of the typical one, then the resulting conception would have 92 chromosomes. Fertilization of an egg cell by two sperm cells instead of one is an error in fertilization known as polyspermy.
- "Chromosome Changes." Center for Genetics Education. 30 Sept. 2015. Web. 6 Jan. 2016.
- "Polyploidy." Nature.com. Nature Publishing Group, 5 July 2009. Web. 6 Jan. 2016.