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Meiosis- An Overview. Reduces number of chromosomes from a diploid (2n) number to a haploid (n) number Gametes, sex cells, have a haploid number of chromosomes until they fuse together to make a diploid zygote Diploid organisms (2n) have x number of homologous pairs of chromosomes .
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Meiosis- An Overview • Reduces number of chromosomes from a diploid (2n) number to a haploid (n) number • Gametes, sex cells, have a haploid number of chromosomes until they fuse together to make a diploid zygote • Diploid organisms (2n) have x number of homologous pairs of chromosomes
Homologous Chromosomes At what stage of the cell life cycle was this photo taken? How would you describe these chromosomes?
Genetic Variation • The whole purpose of sex and meiosis • Occurs through crossing over and independent assortment of homologous chromosomes • Crossing Over • Occurs between non-sister chromatids during the bivalent or tetrad formation • Swap maternal and paternal alleles to create recombined chromatids • Independent Assortment • At metaphase I, tetrad homologues orient the maternal and paternal to opposite polls at random • This create 2x number of combinations…. X being number of paired chromosome in the organism
Significance of Genetic Variation • Allows population to survive as the environment changes
Meiosis Meiosis Animation, Sumanas Inc Meiosis Animation, YouTube Meiose, YouTube
The Life Cycle Animal Plant oogenesis spermatogenesis