2.8, 2.9 Stem cells in embryos, animals and plants + benefit/ risks of their use in medicine

Question 1

What is a stem cell?

Answer 1

unspecialised cells that can differentiate into any type of cell.

Question 2

Examples of stem cells

Answer 2

• embryonic stem cells
• adult stem cells
• meristems in plants

Question 3

Factors of embryonic stem cells

Answer 3

• 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 these cells and direct them to differentiate into almost any cell in the body
• These could potentially be used to replace insulin-producing cells in those suffering from diabetes, new neural cells for diseases such as Alzheimer’s, or
  nerve cells for those paralysed with spinal cord injuries.

Question 4

Factors of adult stem cells

Answer 4

• If found in bone marrow they can form many types of cells (e.g. blood cells)

Question 5

Factors of meristem in plants

Answer 5

• Found in root and shoot tips
• They can differentiate into any type of plant, and have this ability throughout the life of the plant
• They can be used to make clones of the plant - this may be necessary if the parent plant has certain desirable features (e.g. disease resistance), for research or to save a rare plant from extinction

Question 6

What is therapeutic cloning?

Answer 6

an embryo being produced with the same genes as the patient

Question 7

Factors of therapeutic cloning

Answer 7

• The embryo produced could then be harvested to obtain the embryonic stem cells.
• These could be grown into any cells the patient needed, such as new tissues or organs.

Question 8

Benefits of research with stem cells

Answer 8

• 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

Answer 9

• 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 is 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 on other areas of medicine.