stem cells

• What are stem cells?

  undifferentiated (unspecialised) cells that can differentiate by mitosis in specialised cells.
• What are embryonic stem cells?

  -only found in an embryo

  -unspecialised and can differentiate and specialise into any type of cell.
• Advantages of embryonic stem cells

  -can differentiate and become any type of specialised cell

  -it is important to cure incurable diseases

  -most embryos used come from IVF clinics
• Disadvantages of using embryonic stem cells

  -results in destroying the embryo

  -can divide uncontrollably by mitosis to form a lump of cells called a tumour (can cause cancer)
• You cut your skin accidently and new skin cells grow. You have skin stem cells around the wound. Explain how these develop to form new skin cells. (3 marks)

  -stem cells are unspecialised.

  -they will become new skin cells by differentiation by dividing by mitosis to make specialised cells.

  -these new skin cells will replace the damaged skin cells.
• What are adult stem cells?

  -only found in adult bone marrow

  -unspecialised cells and can differentiate and specialise into a few different cells e.g. white and red blood cells and platelets
• Advantages of adult stem cells

  -their production doesnt destroy an embryo - no ethical issues
• Disadvantages of adult stem cells

  -can differentiate by mitosis but only become a few types of specialised cell
• Risks of using stem cells

  -risk of rejection

  -can divide uncontrollably by mitosis to form a lump of cells called a tumour(cancer)
• Scientists have now discovered that they can make adult stem cells behave like embryonic stem cells. Discuss the benefits of this research (3 marks)

  -means that adult stem cells can now differentiate and become any type of specialised cell.

  -therefore, no embryos will be destroyed

  -can cure incurable diseases

  -there will be no rejection