B1.14

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  • Created by: spud99
  • Created on: 13-04-15 13:59
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  • B1.14
    • mutations
      • change structure of gene
      • spontaneous
        • no external cause, mistake whilst DNA copied before cells divide
      • caused by environment
        • chemicals in tobacco
        • chemicals in dying materials
        • UV radiation from sunlight
        • ionising radiation
          • x-rays
    • alleles
      • different version of a gene that codes for the same characteristics BUT produce a slightly different version of them
    • causes of genetic variation
      • mutations
      • formation of gametes
      • fertilisation
    • gametes
      • sex cells
        • female - eggs
        • male - eggs
      • each one genetically different
      • 23 chromosomes
      • made by meiosis of body cell
        • 23 pairs of chromosomes in the body cell separate
        • genetic variation during meiosis
          • chromosomes swap pieces , different allele combination but same genes
          • way two copies separate is random
    • fertilisation
      • random
      • produces genetic variation
        • 1 male gamete + 1 female gamete
          • new individual with full number of chromosomes

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