Stem cellsSpec 4.1.2.3
- Stem cell
- An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.
You should be able to describe the function of stem cells in embryos, in adult animals and in the meristems in plants.
| Where | What the stem cells can do |
|---|---|
| Human embryos | Can be cloned and made to differentiate into most different types of human cell |
| Adult bone marrow | Can form many types of cell, including blood cells |
| Plant meristems | Meristem tissue can differentiate into any type of plant cell, throughout the life of the plant |
Knowledge and understanding of stem cell techniques are not required.
Medical uses
Treatment with stem cells may be able to help conditions such as diabetes and paralysis.
In therapeutic cloning an embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient's body, so they may be used for medical treatment.
Risks and objections
- There are potential risks, such as transfer of viral infection.
- Some people have ethical or religious objections to the use of stem cells from embryos.
Plant stem cells
Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.
- Rare species can be cloned to protect them from extinction.
- Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.
Quick check
What are chromosomes made of, and where are they found?
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DNA molecules, in the nucleus.
Name the three overall stages of the cell cycle.
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Growth and DNA replication; mitosis; division of the cytoplasm and cell membranes.
What does mitosis produce?
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Two genetically identical cells.
Why are stem cells from therapeutic cloning not rejected?
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The embryo has the same genes as the patient.
Where are stem cells found in plants?
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In meristems, throughout the life of the plant.