# 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)
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# 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:
- Type 1 Diabetes
- Spinal injuries
- Many more
# Stem Cell Ethics
- Playing god
- Religious objections