Definition

Noun: - A failure of separation during cell division: Specifically, "nondisjunction" refers to the failure of homologous chromosomes or sister chromatids to separate properly during meiosis or mitosis. This error results in daughter cells that have an abnormal number of chromosomes (aneuploidy).

Usage

• Scientific/Biological Context: The term is used almost exclusively in genetics, cytology, and cell biology to describe a specific type of chromosomal error.
  • Nondisjunction is a primary cause of genetic disorders such as Down syndrome.
  • Researchers studied the mechanism of nondisjunction in the developing egg cells.

Examples

• The genetic condition was caused by a event in the mother's gametes.
• during meiosis I leads to gametes with missing or extra chromosomes.
• Advanced maternal age is a known risk factor for .

Advanced Usage

• "Nondisjunction error": A phrase emphasizing the mistake itself.
  • The embryo was not viable due to a severe nondisjunction error.
• Specifying the stage: can be specified as occurring in meiosis I, meiosis II, or mitosis, with different genetic outcomes.

Variants and Related Words

• Disjunction (n): The correct and normal separation of homologous chromosomes or sister chromatids during cell division. (This is the opposite process).
• Aneuploidy (n): The state of having an abnormal number of chromosomes, which is a direct result of nondisjunction.
• Trisomy (n): A type of aneuploidy where there are three copies of a particular chromosome instead of two (e.g., Trisomy 21, or Down syndrome).

Synonyms

• Chromosomal malsegregation: A more technical synonym used in scientific literature.
• Separation failure: A simple, descriptive phrase for the event.

Antonyms

• Disjunction: The proper separation of chromosomes.
• Normal segregation: The correct distribution of genetic material.

Noun

1. meiosis in which there is a failure of paired homologous chromosomes to separate; results in an abnormal number of chromosomes in the daughter cells