Microsoft PowerPoint - Genetic Engineering - GENETIC...

Microsoft PowerPoint - Genetic Engineering
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GENETIC ENGINEERING BY S.M. RAFIGH
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Role of Mutation Change in structure or amount of an organism’s genetic material Change in genotype produces change in phenotype = mutant 2 types of mutation . ۱ Chromosome mutation . ۲ Change in structure of one chromosome
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Chromosome mutations Change in chromosome number . ۱ Non-disjunction in meiosis . ۲ Non-disjunction of sex chromosomes . ۳ Complete non-disjunction and polyploidy
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Non-disjunction during meiosis Spindle fibre fails during meiosis Members of one pair of homologous chromosomes fail to become separated 2 gametes receive extra copy of affected chromosome 2 gametes lack that chromosome
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Down’s Syndrome r Non-disjunction in chromosome 21 r Occurs in human egg mother cell r One or more abnormal eggs formed (n = 24) r Fertilised by normal sperm (n = 23) r Formation of abnormal zygote (2n = 47)
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chromosomes
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