A stem cell is an undifferentiated cell. It can divide to make more stem cells and can differentiate into certain specialised cells.
These are different abilities: division makes more cells; differentiation changes what a cell can do.
Embryonic stem cells can form most types of human cell. This makes them useful in research into replacing damaged cells.
Adult stem cells can form a more limited range of cell types. Bone marrow stem cells make blood cells; bone marrow transplants are an established treatment for some blood disorders.
Meristems are growing regions, such as root and shoot tips. Their stem cells can form any type of plant cell throughout the plant’s life.
Scientists investigate whether stem cells could replace damaged cells in conditions such as diabetes and paralysis. Potential treatments are not the same as guaranteed cures.
| Consider | Example |
|---|---|
| Benefit | Replace damaged cells and restore a function. |
| Risk | Viral infection could be transferred; cells might divide uncontrollably. |
| Ethical issue | Some people object to destroying embryos; others give greater weight to possible medical benefits. |
An embryo is produced with the same genes as the patient. Its stem cells are genetically matched, so the patient’s immune system is much less likely to reject them.
The aim is to obtain cells for treatment, not to produce a cloned baby. You do not need the detailed technique here.
Meristem stem cells can be used to grow many genetically identical plants quickly and economically.
This can help preserve rare species or produce crops with useful features, such as disease resistance.
Challenge: genetically identical crops have little genetic variation. If a new disease can infect that variety, many plants may be affected.
Stem cells divide and differentiate. Embryos, adult bone marrow and plant meristems are important sources. Weigh benefits against risks and ethical concerns.
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