Abnormal meiosis Grade 12 Life Sciences Notes with Activities Questions and Answers Meiosis is a crucial process in sexual reproduction, where cells divide to produce gametes with half the chromosome number of the parent cell. Abnormalities in meiosis can lead to various genetic disorders and anomalies. Understanding these abnormalities is essential for comprehending genetic inheritance and its implications.

Notes

Sometimes mistakes occur during the process of meiosis.

• This can happen in Anaphase 1 where the homologous chromosomes may not separate. Also called non-disjunction.
• It can also happen in Anaphase 2 when there is non-disjunction of the sister chromatids.
• If there is non-disjunction of chromosome pair 21 in humans it leads to the formation of an abnormal gamete with an extra copy of chromosome 21.
• If there is fusion between a normal gamete and an abnormal gamete (with extra copy of chromosome 21) it leads to Down Syndrome.

If meiosis does not occur properly, an egg or sperm could end up with too many chromosomes, or not enough chromosomes.

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