Stem cells

• A stem cell is an undifferentiated cell which can differentiate to form other types of cells
• Stem cells are found in embryos, bone marrow and blood
• Stem cells in bone marrow form red blood cells, white blood cells and platelets
• Leukaemia is a cancer of bone marrow, to treat this the patient's existing bone marrow is destroyed using radiation, then they receive a transplant of bone marrow from a donor, the stem cells now divide and form new bone marrow. They also differentiate and form blood cells
• The donor MUST be compatible with the patient, otherwise the white blood cells produced by the donated bone marrow could attack the patient's body.
• There is a risk that viruses can be passed from donor to patient
• In therapeutic cloning, an embryo is produced with the same genes as the patient.
• Stem cells from the embryo can be transplanted into the patient without being rejected
• Roots and buds contain meristem tissue. These stem cells can differentiate into any type of the plant tissue at any point in the life of the plant
• We could clone a rare plant to stop it from going extinct or produce cloned crops for farmers