Stem cells

• • A stem cell is an undifferentiated cell ithan can undergo specialisation
• Adult stem cells:

  • Found in bone marrow
  • Can only specialise into blood cells
  • Can cure disease - stem cells transferred from bone marrow of healthy person can replace faulty blood cells in patient
• Embryonic stem cells:

  • Can be grown in lab to produce clones of desired cells
  • Can replace faulty cells - making insulin producing cells for people with diabetes, nerve cells for paralysis
  • Therapeutic cloning - embryo produced with same genes as patient so stem cells are not rejected from body
• Risks of embryonic stem cell use:

  • Each embryo is human life
  • Stem cells grown in lab can be contaminated with virus and passed onto patient
  • Stem cell research banned in some countries
• Benefits of stem cell use:

  • Curing suffering patients is more important that life of embryos
  • Embryos used are unwanted
• Stem cells in meristems:

  • Stem cells in meristem can differentiate into any type of cell at any point in life
  • Can be used to produce clones quickly and economically
  • Can be used to clone rare species facing extinction
  • Csn be used to clone crops of identical plants that have desired features e.g disease resistance
• therapeutic cloning:

  • stem cells would not be rejected by immune system

  1. remove nucleus of cell from patient
  2. nucleus from donor egg cell removed
  3. nucleus transferred to donor egg cell
  4. cell stimulated to divide
  5. cell develops into embryo
  6. stem cells removed and cultured
• disadvantages of using stem cells:

  • difficulty in finding stem cell donors
  • cultured stem cells could have viruses which could be transferred to patient
  • difficulty in storing embryonic stem cells