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Dictionary » N » Nondisjunction

Nondisjunction

Definition

noun

(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.


Supplement

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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Results from our forum


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: 282

GOT A QUESTION

... 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
Topic: GOT A QUESTION
Replies: 2
Views: 737

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: 488

Chromosomes

If you have XXY or more than 2 Xs and a Y you have something callled Nondisjunction or trisomy. This generally means that you develop down syndrome during development. You can't have a YY because YY only codes for a certain number of chromsomes. You must have ...

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by daniel.kurz
Fri May 19, 2006 2:01 am
 
Forum: Genetics
Topic: Chromosomes
Replies: 17
Views: 4125

Nondisjunction of chromosomes

Hello, i know that nondisjunction in chromosomes occur in meiosis II, when the sister chromatids fail to separate and both daughter chromosomes go into the same gamete. My doubt is in this question where i think the correct one is ...

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by Elliott
Fri May 05, 2006 11:12 pm
 
Forum: Genetics
Topic: Nondisjunction of chromosomes
Replies: 2
Views: 1228
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