6.5 Stem Cells

Question 1

Define stem cell

Answer 1

Stem cells are unspecialised cells that can differentiate to become a specialised cell type

Question 2

Define potency

Answer 2

A stem cell’s ability to differentiate into different cell types
The greater the number of cell types it can different into, the greater its potency

Question 3

3 types of potency?

Answer 3

Stems cells differ depending on the type of cell they can turn into:

• totipotent: these stem cells can differentiate into any type of cell
• pluripotent: these stem cells can form all tissue types but not whole organisms
• multipotent: these stem cells can only form a range of cells within a certain type of tissue

Question 4

Describe differentiation using erythrocytes and neutrophils as an example

Answer 4

Erythrocytes and neutrophils are both present in blood. They look very different because they have different functions. When cells differentiate they become adapted to their role.

All blood cells are derived from stem cells in the bone marrow. Erythrocytes and neutrophils have a limited lifespan therefore stem cell colonies in the bone marrow need to be constantly producing these.

Question 5

Sources of animal stem cells?

Answer 5

• embryonic stem cells at early stage of embryo are totipotent and blastocyst cells are pluripotent
• adult stem cells are multipotent

Question 6

Sources of plant stem cells

Answer 6

• stem cells are present in meristematic tissue
• found at root tips and shoots and vascular cambium (between phloem and xylem tissues)
• cells from cambium differentiate into xylem and phloem tissues

Question 7

Uses of stem cells

Answer 7

Have the potential to treat diseases such as:

• type 1 diabetes
• heart disease
• Parkinson’s disease
• Alzheimer’s disease

Question 8

Ethics concerning use of stem cells?

Answer 8

• the removal of totipotent or pluripotent cells from embryo result in destruction of the embryos and this goes against religious views