Dictionary » N » Nondisjunction




(In mitosis) The failure of sister chromatids to separate during and after mitosis.

(In meiosis) The failure of homologous chromosomes to segregate or to separate during and after meiosis.


This could result to a condition wherein the daughter cells have an abnormal number of chromosomes; one cell having too many chromosomes while other cell having none.

Examples of nondisjunction:

Related forms: nondisjunctional (adjective).
Related terms: meiotic nondisjunction.

Compare: disjunction.
See also: anaphase.

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Using Colchicine for Polyploids

So I was wondering... Colchicine is used to create polyploid plants. It acts as a mitotic spindle poison which can cause nondisjunction of the entire genome. What I was wondering was that if you were to treat a seed with a colchicine solution, is the disjunction of the entire genome ...

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by plasmodesmata11
Tue Jul 19, 2011 10:50 pm
Forum: Genetics
Topic: Using Colchicine for Polyploids
Replies: 0
Views: 1832

Aneuploidy and Mosaicism

... will lead an organism to unwanted results? Do chromosomes of the same type code for the same genetic information? 2. Mosaicism happens if nondisjunction happens during cell division of an embryo. If a normal disomic cell undergoes mitosis, and one of the outcome is a trisomic cell, then ...

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by Procon1234
Sun Jan 09, 2011 3:23 pm
Forum: Genetics
Topic: Aneuploidy and Mosaicism
Replies: 4
Views: 2629

Regarding Mutation

... Down syndrome. It is the cause of 2–3% of observed cases of Down syndrome. 95% of the observed cases of Trisomy 21 is anueploidy caused by meiotic nondisjunction events in the parental gametes (88% in the female gamete, and 7% in the male gamete).

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by kolean
Sun Jul 12, 2009 8:37 pm
Forum: Genetics
Topic: Regarding Mutation
Replies: 5
Views: 6452


... The karyotype was taken from a man that had XYY disorder. The question was how does one go about inheriting the XYY disorder. I explained about nondisjunction during meiosis and subsequent formation of gametes. And also, I think the XYY disorder is actually not necessarily inherited genetically, ...

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by biotchr
Mon Mar 05, 2007 5:00 am
Forum: Human Biology
Replies: 2
Views: 2012

Down syndrome

... you need to determine the chance that a second child would suffer from the condition? My answers: a The most likely cause of trisomy-21 would be nondisjunction b/c firstly it is her sixth child (suggesting that it is not within her phenotype), secondly her age. b ?????

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by student12
Tue Aug 15, 2006 8:53 am
Forum: Genetics
Topic: Down syndrome
Replies: 1
Views: 1602
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