Stem Cells

  • A stem cell is an undifferentiated cell that can differentiate itself
  • Undifferentiated means that it currently performs no function in the body
  • Division of stem cells can cause tumours and cancers (in rare cases)

Stem Cell Potency

  • Potency: The number of cells it can differentiate into
  • Totipotent: Can differentiate into any type of cell, able to form a whole organism & a placenta.
  • Pluripotent: Any tissue but not a whole organism.
  • Multipotent: A small range of cell types within a tissue.


  • A multicellular organism is able to evolve specialised tissues to optimise efficiency.
  • Blood cells have a different shape and less organelles, to improve their oxygen carrying capacity. This makes them highly specialised to their specific role.

Replacement of Blood Cells

  • Red blood cells must be produced by stem cells because they have no nucleus and few organelles, making self division impossible.
  • The stem cells that produce new red blood cells are located in the bone marrow.
  • A neutrophil (type of white blood cell) can live for up to 6 hours and you can produce 1.6 billion per kg of stem cell tissue per hour.

Sources of Animal Stem Cells

  • Embryonic & Tissue stem cells
  • Embryonic stem cells are totipotent whereas adult tissue stem cells are pluri or multipotent
  • A sample can be extracted and grown into tissues to help someone recover from an illness of injury

Sources of Plant Stem Cells

  • Meristem, roots, shoots, tips
  • Pluripotent (meristem)
  • Used for tissue growth and repair

Uses of Stem Cells

  • Diseases that they can already provide treatments that they can already provide:
    • Alzheimer’s
    • Type 1 Diabetes
    • Spinal injuries
    • Many more

Stem Cell Ethics

  • Playing god
  • Religious objections