stem cells

• stem cells are unspecialised cells
• • multicellular organisms are made from different cell types that are specialised for their function e.g. liver cells
  • all these specialised cell types came from stem cells|
  • stem cells are unspecialised and can develop into different typesall multicellular organisms have some form of stem cell
  • found in early embreyos - can develop into any cell
  • adults - limited range of cells
• stem cells differentiate into specialised cells
• • stem cells divide to become new ccells which become specialised
  • when a cell becomes specialised - differentiation
  • animals - adult stem cells replace damages cells e.g. skin
  • plants - always growing so neede for new shoots and roots throught their lives. can differentiate into various tissues including xylem and phloem
  • able to divide to produce more undifferentiated stem cells i.e. renew
• cells in the bone marrow differentiate into blood cells

  • bones are living organisms, contain nerves and blood vessels
  • bones have marrow
  • in marrow adult stem cells divide and differentiate to replace worn out blood cells - erythrocytes (red) and neutrophils (white help fight infection)
• cells in meristem differentiate into Xylem and Phloem

  • in plants there found in meristems
  • in the root and stem, stem cells of the vascular cambium divide and differentiate to become xylem vessels and phloem sieve tubes
• stem cells can cure diseases such as Parkinson's

  • Alzheimer's - nerve cells in the brain die researchers hope to use stem cells to re grow healthy nerves
  • Parkinsons - suffer from tremors and causes loss of nerve cell found in brain which release dopamine to control movement. transplanted stem cells may help regenerate new ones