Cell division and stem cells

• Stem cells


  Undifferentiated cells that can differentiate into any other type of cell
• Sources of stem cells

  • Embryonic tissue
  • Adult stem cells that occur in some tissue
• Stem cells


  • Can be used to replace damaged or diseased tissue
  • Have many medical applications
• If possible, it is better to use your own stem cells

  • No rejection
  • No need to find a donor
  • No need for tissue typing
  • Avoids the use of embryonic stem cells which raises particular ethical issues
• Mitosis


  A type of cell division which organisms use for growth, repair of damaged cells, and replacement of old cells
• Mitosis


  • Produces 2 daughter cells
  • Each daughter cell is genetically identical and has the same number of chromosomes as the mother cell
• Meiosis


  The type of cell division which only occurs for formation of sex cells (gametes) like eggs and sperm for sexual reproduction
• Genes


  Code for characteristics
• Chromosomes


  Linear arrangements of genes
• Allele


  A different version of the same gene
• Mitosis


  1. Mother cell has 4 chromosomes (2 pairs)

  2. DNA replicates and one copy of each chromosome goes into each cell
• Meiosis


  1. Mother cell has 4 chromosomes (2 pairs - Diploid)

  2. DNA replicates but the chromosome and its copy remain attached

  3. One of each pair of chromosomes goes into a new cell

  4. 4 new cells are formed

  5. Each cell has half the chromosomes the mother cell has - they are haploid

  6. Cells are not genetically identical to the mother cell
• Cancer is the result of uncontrolled mitosis