Abnormal meiosis Grade 12 Life Sciences Study Notes . On this page you will find Abnormal meiosis Grade 12 Life Sciences Notes under Meiosis, which includes revision activities with questions and answers to help grade 12 learners to prepare for their tests and exams.
Abnormal meiosis Grade 12 Life Sciences Study 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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