Stem Cells

• 2 type of stem cells found in plants:

  • Adult stem cells.
  • Embroyonic stem cells.
• 2 features of stem cells:

  • They can divide by mitosis to form more cells.
  • They can differenstiate into specialised cells.
• Adult stem cells can only differensiate into different type of blood cells.
• 1. When a sperm cell fertilises an egg cell they form a single cell (zygote).
  2. The zygote then divides by mitosis to form a ball of cells which we call an embryo.
  3. The cells in an embryo are known as embryonic stem cells which can differensiate into any type of cell.
• Adult stem cells are found in the bone marrow in the human body.
• Plant tissues that are continiously growing and contain stem cells are called meristems.
• The meristems are located:

  • In the stem.
  • Tips of the shoot.
• Ways sperm cells are adapted to thier roles:

  • Contain lots of mitochondria which gives them lot of energy to move around.
  • Contains a flagellum to allow it to swim to the egg cell.
  • Contains digestive enzymes in its head to break through the walls of the egg cell.
  • It is streamlined to make it swim faster.
• Root hair cells and red blood cells are adapted to thier roles by having a large SA.
• Cells that can perform a specific function are called specialised cells.
• Steps of stem cell treatment:

  1. Extract embryonic stem cells from early embryos.
  2. Grow them in a laboratory.
  3. Stimulate them to differensiate them into any type of specialsed cell you want.
  4. Give them to the patient to replcae thier faulty cells.
• Drawbacks of using embryonic stem cells:

  • Ethical issues.
  • Risk of rejection.
  • Stem cell supply is limited.