Stem Cells (1.2.3)

What is a stem cell?

An undifferentiated cell which can undergo division to produce many more similar cells, of which some will differentiate to have different functions.

What are the types of stem cells?

embryonic, adult stem cells, meristems in plants

What are embryonic stem cells?

• They form when an egg and sperm cell fuse to form a zygote.

• They can differentiate into any type of cell in the body.

• Scientists can clone them through culturing and direct them to differentiate into almost any cell in the body.

• They could potentially be used to replace insulin-producing cells in those suffering from diabetes, new neural cells for diseases like Alzheimer’s, or nerve cells for those paralysed with spinal cord injuries.

What are adult stem cells?

• Found in bone marrow.

• Cannot form into any cell type, but can form many certain types of cells including blood cells.

• They can cure some diseases (e.g. stem cells transferred from a healthy person’s bone marrow to replace faulty blood cells in the patient.)

What are meristems?

• Found in root and shoot tips.

• They can differentiate into any type of plant, and have this ability throughout the life of the plant.

• Can make clones of the plant - e.g. if the parent plant has certain desirable features (like disease resistance) for research or to save a rare plant from extinction.

What is therapeutic cloning?

This involves an embryo being produced with the same genes as the patient.

What is the process of therapeutic cloning?

• The embryo produced is harvested to obtain the embryonic stem cells.

• These can be grown into any cells the patient needs, such as new tissues or organs.

• The advantage is that they will not be rejected as they would have the exact same genetic make-up as the individual.

What are the benefits of research with stem cells?

• Can be used to replace damaged or diseased body parts.

• Unwanted embryos from fertility clinics could be used as they would otherwise be discarded.

• Research into the process of differentiation.

• Curing patients who are suffering is more important than the rights of embryos.

What are the problems of research with stem cells?

• We do not completely understand the process of differentiation, so it is hard to control stem cells to form the cells we desire.

• Removal of stem cells results in destruction of the embryo.

• People may have religious or ethical objections as it seen as interference with the natural process of reproduction.

• If the growing stem cells are contaminated with a virus, an infection can be transferred to the individual.

• Money and time could be better spent into other areas of medicine.