meosis

• meosis

  • only takes place in sex organs
  • only used to produce gametes
  • starts as one diploid cell=4 haploid gametes , containing individual chromosomes not pairs
  • all gametes are genetically different
• variation- crossing over

  • at early state, 2 homologous chromosome pairs come together
  • chromatids of 2 chromosomes wrap around eachother, attached pairs=bivalent
  • points where chromatids join=chiasmata
  • parts of chromatids break off and exchange alleles between homologous chromosomes
  • =recombinant chromosomes(exchange of alleles)-major source of genetic variation
• independant assortment

  • when homologous chromosome pairs line up on the spindle
  • cannot predict whether paternal or maternal chromosome will end up in which gamete
  • =4 genetically different cells and each cells have different alleles depending if maternal or paternal
• independant assortment


  2 to the power of 23(number of homologous chromosome pairs)=over 8 million genetically different gametes