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biologydictionary.net/nondisjunction

Nondisjunction occurs in cell division when chromosomes do not divide properly. Chromosomes contain all of a cell’s DNA, which it needs in order to function and reproduce. Normally, when a cell divides, the chromosomes line up in an orderly way and then separate from each other before cell division.

www.lecturio.com/magazine/nondisjunction

Nondisjunction connotes the failure of the separation of homologous chromosomes during cell division. It has significant repercussions and is culpable for a large share of chromosomal anomalies like aneuploidy and various hereditary syndromes.

study.com/academy/lesson/nondisjunction-in-meiosis...

Nondisjunction during meiosis produces eggs or sperm cells that don't have the normal number of chromosomes. In this lesson, learn about the process of nondisjunction and problems it can cause in ...

en.wikipedia.org/wiki/Nondisjunction

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division.There are three forms of nondisjunction: failure of a pair of homologous chromosomes to separate in meiosis I, failure of sister chromatids to separate during meiosis II, and failure of sister chromatids to separate during mitosis. ...

medical-dictionary.thefreedictionary.com/Chromosomal...

nondisjunction [non″dis-jungk´shun] failure either of two homologous chromosomes to pass to separate cells during the first meiotic division, or of the two chromatids of a chromosome to pass to separate cells during mitosis or during the second meiotic division. As a result, one daughter cell has two chromosomes or two chromatids, and the other has ...

www.answers.com/Q/What_is_an_example_of_nondisjunction_in...

Nondisjunction is the failure of a homolog to separate during meiosis causing trisomy (an extra chromosome) or monosomy (a missing chromosome), it can be harmful because it is a mutation that can ...

medical-dictionary.thefreedictionary.com/nondisjunction

nondisjunction [non″dis-jungk´shun] failure either of two homologous chromosomes to pass to separate cells during the first meiotic division, or of the two chromatids of a chromosome to pass to separate cells during mitosis or during the second meiotic division. As a result, one daughter cell has two chromosomes or two chromatids, and the other has ...

www.sciencedirect.com/.../nondisjunction

Most numeric chromosomal abnormalities are caused by nondisjunction. Examples include: Down syndrome (trisomy 21): The incidence is 1 in 1000 for women up to their mid-30s, but 1 in 30 for women at age 45 years. Most cases are accounted for by nondisjunction during the first meiotic division (meiosis I) of oogenesis.

www.wisegeek.com/in-genetics-what-is-nondisjunction.htm

When carried through in genetics, nondisjunction can result in either the sperm or the egg cells of the parent possessing 24 chromosomes instead of the normal 23. In these cases, the child conceived will have 47 chromosomes, which is the common variation known as trisomy, seen in children with Down syndrome.

www.biology.iupui.edu/biocourses/N100/2k2humancsomal...

(The other chromosomes are distributed normally.) If either of these gametes unites with another during fertilization, the result is aneuploidy (abnormal chromosome number) A trisomic cell has one extra chromosome (2n +1) = example: trisomy 21. (Polyploidy refers to the condition of having three homologous chromosomes rather then two)