Question
What happens when chromosomes fail to segregate during cell division cycle? Explain your answer with an example.
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Answer
- The failure of chromosomes to segregate during cell division cycle i.e., non-disjunction leads to aneuploidy, i.e., loss or gain of chromosome(s).
- Down's syndrome results due to trisomy of 21st chromosomes, i.e., due to non-disjunction of 21st chromosomes during gamete (ova) formation
- When such an ovum with two copies of 21st chromosome is fertilised by a normal sperm the zygote comes to possess three copies of 21st chromosome trisomy).
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