CELL DIVISION B2

• Cell division


  The process where a cell divides into two or more identical cells
• Cell cycle


  1. Growth

  2. DNA Synthesis

  3. Chromosomes align

  4. Mitosis
• Mitosis


  • Occurs during growth & to repair or replace damaged cells
  • Occurs in both plants and animals
• Stem cells


  Undifferentiated cells within an organism that can produce other stem cells and then differentiate into many different types of cells
• Human embryo stem cells

  • Can be cloned and made to differentiate into most types of human cells
  • Have the same genes as the patient, so not rejected by the body
• Human adult stem cells

  • Can form many (but not all) types of cells including blood cells
  • Can be used to help treat diseases like diabetes and paralysis
• Embryos produced by therapeutic cloning have the same genes as the patient
• Using stem cells has risks such as transfer of viral infections
• Some people have objections to stem cell use for ethical religious reasons
• During fertility treatment, doctors usually fertilize many more eggs than going to be used, and the embryos formed are used to obtain stem cells
• In the UK, scientists can use these embryos for research, but only under very strict guidelines
• Plant stem cells


  Undifferentiated cells that can differentiate into most types of plant cells and are grouped together in structures called meristems
• Plant stem cells


  • Can be used to quickly and economically produce clones of plants
  • Can be used to clone crop plants with special features like disease resistance
• Stem cell sources


  • Embryonic stem cells
  • Adult bone marrow
• Name 3 types of stem cells

  embryonic stem cell . Adult stem cell . Plant meristems
• Where are adult stem cells found ?

  Specific parts of the body in adults and children
• Where are embryonic stem cells found ?

  Early human embryos often taken from spare embryos from fertile centres
• Where are meristms found ?

  Meristem regions in roots and shoots of plants
• Embryonic ( PROS )

  Can treat range of diseases . No donor is needed which means many are avaliable . Painless
• Embryonic (CONS)

  Risk of transferring viral infections. Newer treatment so its unreliable .Possible harm.
• Adult bone marrow ( PROS )

  Quick recovery . Safe .Well tested
• Adult bone marrow (CONS)

  Few diseases treated . Requires a donor meaning long time to wait .Painful