MEIOSIS AND DOWN SYNDROME ESSAY
Describe how meiosis contribute to genetic variation and how abnormal meiosis leaf to down syndrome and polyploidy. Also describe advantages of polyploidy in agriculture.Meiosis
❖ Crossing over occurs during prophase1
❖ Homologous chromosome pair up
❖ Each chromosome has two chromatids
❖ Chromatids overlap
❖ At point called chiasma
❖ To exchange genetic material
❖ Between non-sister chromatids
❖ Each gamete will have mixture of genes from both parents
❖ Which brings about variation
❖ Random arrangement of chromosomes at equator
❖ Each pair of homologous chromosomes
❖ May line up either way on spindle
❖ Independently of each other
❖ Genetics will form differing mix of parental chromosomes.
Down syndrome
❖ In meiosis1 chromosome pair 21 fails to separate
❖ In meiosis2 chromatics of chromosome 21 fails to separate
❖ Referred to as Non-disjunction
❖ One gamete will have extra copy of chromosome 21
❖ If this gamete fuses with normal gamete
❖ The resulting zygote will 47 chromosomes
❖ Leading to down syndrome.
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