stem cells (chapter 6)

Question 1

what are stem cells

Answer 1

undifferentiated cells that have the potential to differentiate into any type of cell.
- stem cells are able to undergo division over and over again.
-once stem cells have become specialized hey are unable to divide again.

Question 2

totipotent stem cells

Answer 2

• these stem cells can differentiate into any type of cell.
• can also differentiate into extra-embryonic divisions.
• they are the cells from its first few mitotic divisions.
• can form whole organisms

Question 3

pluripotent stem cells

Answer 3

• can form all tissue types but not whole organisms
• present in early embryos

Question 4

multipotent stem cells

Answer 4

• can only form a range of cells within a certain type of tissue
• hematopoetic stem cells in bone marrow are multipotent because this gives rise to various types of blood cell

Question 5

sources of animal stem cells

Answer 5

embryonic stem cells : are present in very early stage of embryo development and are totipotent. After about 7 days a blastocyst has formed and the cells are now pluripotent state. They remain this state in the fetus until birth.
Tissue stem cells : present throughout life from birth. Found in specific areas such as bone marrow, they are multipotent. stem cells can also be harvested from umbilical cords, these stem cells can be stored unless they are ever needed in the future.

Question 6

ethics

Answer 6

• stem cells have been used in medicine for many years in the form of bone marrow transplants.
• embryos can be created in the laboratory as a source of stem cells.
• the removal of stem cells from embryos normally results in the destruction of embryos, these are not only religious objections to the use of embryos but moral objections too.
• many people believe life begins at conception, therefore the destruction of embryos counts as murder.
• the controversy is holding back the process of finding treatments for incurable diseases.