What is chromosomal nondisjunction in meiosis?
Chromosomal nondisjunction is a type of error that can occur during meiosis where
chromosomes fail to separate properly. This results in an abnormal distribution of
chromosomes among the daughter cells, which can lead to genetic disorders such
as Down syndrome, Turner syndrome, or Edwards syndrome.
During meiosis, each of the homologous chromosomes separates, with one copy
going to each of the two daughter cells. However, errors can occur during this
process, particularly during the separation of the sister chromatids in the second
meiotic division. The resulting gametes will then have an abnormal number of
chromosomes, either too many or too few.
The effects of chromosomal nondisjunction can vary depending on which
chromosomes are affected and how many are involved. In many cases, the resulting
embryo will not be viable and will either fail to implant or be miscarried. However, if
the embryo survives, it may have a range of physical and intellectual disabilities.
Chromosomal nondisjunction can occur in both male and female gametes, but it is
more common in older women. This is because the chance of errors occurring
increases with age due to changes in the structure of the chromosomes.
In conclusion, chromosomal nondisjunction is a significant cause of genetic
disorders, and careful monitoring is necessary to ensure that an individual with this
condition can receive appropriate care and support.
References:
- Griffiths AJ et al. An Introduction to Genetic Analysis. W. H. Freeman; 2000.
- Hartwell LH et al. Genetics: From Genes to Genomes. McGraw-Hill Higher Education;
2017.