3. meiosis

• haploid cell?

  half number of chromosomes in a somatic cell, other than gametes
• diploid cell?

  full number of chromosomes in a somatic cell
• 2 important roles of meiosis?

  genetic variation among offspring

  haploid cells produced that maintain a diploid number after fertilisation
• overview of meiosis?

  • Meiosis 1- homologous chromosomes separate as spindle fibres contract (line up in pairs)
  • Meiosis 2- sister chromatids separate, producing 4 gametes
• independent assortment?

  random aligning of maternal and paternal chromosomes along equator of cell, producing new combination of chromosomes
• crossing over?

  breaking and re-joining non sister chromatids on the same chromosome pair, exchanging alleles. recombination of alleles between chromatids