Non-disjunction of the 21st pair of chromosomes in one of the gametes leads to 47 chromosomes in one individual. This condition is called
Correct answer: C. Down syndrome
- A. Turner's syndrome
- B. Klinefelter's syndrome
- C. Down syndrome
- D. Jacob's syndrome
Explanation
Down syndrome is usually caused by an error in cell division called "nondisjunction." Nondisjunction results in an embryo with three copies of chromosome 21 instead of the usual two. Before or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separate.
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About Chromosomes
Chromosomes are DNA-protein structures that carry genes and become visible during cell division. Coverage includes chromatin, centromeres, sister chromatids, homologous chromosomes, chromosome number, and the distinction between diploid and haploid cells, with links to DNA replication, mitosis and meiosis.
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