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B2 : Cell Division - Coggle Diagram
B2 : Cell Division
Stem cells
Stem cells are undifferentiated cells that can differentiate into any type of specialised cell
An example is an embryonic stem cell, when the cells in an embryo haven't differentiated and is capable of differentiating into any type of body cell
Another example is bone marrow stem cells. Adult stem cells cannot differentiate into any type of cell, but specific types: like bone marrow stem cells can differentiate into any blood cell ( red,white or platelet)
Stem cells are very useful in medicine: bone marrow transplants can help treat people with leukemia after the patient's existing bone marrow is destroyed by radiation. The patient receives a bone marrow transplant and the stem cells in the bone marrow then divide to make new bone marrow and then they differentiate to make new blood cells. But there are drawbacks
the donor has to have the same blood type as the patient, otherwise the new white blood cells will attack the patient's body.Research is being carried to treat:
- spinal cord after injuries
- diabetes
- heart after damage in heart attacks
- eyesight in the blind
- damaged bone
Stem cells in plants
The stem cells from plant meristems can be used to make clones. This is important as it gives us a away of producing large numbers of rare plants reliably and safely. We may be able to save rare plants from extinction and it is useful for research.
In agriculture, cloning plants is used to produce large numbers of identical plants with special features such as disease resistance. Exotic plants like orchids can be cloned and this means they can be relatively cheapand are available for everyone to enjoy
Stem cell dilemmas
Embryonic stem cells come from aborted embryos or from spare embryos donated from fertility treatment because they will not be used. Some people believe it not right as it is a potential human being. The religious beliefs of others mean they can not accept any inteference with the process of human reproduction.Progress and research in using embryonic stem cells has been slow, difficult and expensive and hard to control but doctors have only been working for them for a short time. There are concerns they may cause cancer which was a problem that occured when used to treat mice and in early human treatments.
There are risks that adult stem cells may be infected with viruses and thi may transfer to the patient. If adult stem cells are from an unrelated person then this may trigger an immune response. Scientists hope embryonic stem cells will solve this problem because the body of the mother does not reject the embryo.
Scientists have found embryonic stem cells in the umbilical cord blood of newborn babies and even in the amniotic fluis that surrounds the fetus. Using these instead of the cells from spare embryos may help to overcome some of the ethical concerns.
They are also trying to find ways of growing adult stem cells and they have only managed to develop them into a limited range of cells. Adult stem cells avoid the controversial use of embryonic tissue and they have been used successfully.
The area of stem cell research known as therapeutic cloning has potential but is proving to be difficult. It involves cells from an adult to produce a cloned early embryo of themsevles. These could be used to grow new organs for the original donor and they would not be rejected becuase they have the same genes.
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Information in cells
Each cell has a nucleus containing chromosomes. These carry the genes that contain instruction for making both new cells and all the tissues and organs needed to make an entire new you. A gene is a section of DNA (unique molecule which makes up chromosomes) that controls characteristics.
There are 46 chromosomes in the nucleus of your body cells. They are arranged in 23 pairs one inherited from mother and one from father. Sex cells only have on chromosome from each pair so they have a total of 23 chromosomes.