Stem Cells

Stem cells

• Undifferentiated cells

• With the correct hormonal and genetic signals, stem cells have the ability to become any specialised cells in a body

What is the role of stem cells?

• Replace body cells that die through injury and disease

When do stem cells differentiate?

Only differentiate into cells from the type of tissue where they’re found

where are many undifferentiated cells?

Embryo

Differentiation

Process by which a cell changes to become specialised for its job

What are the cells in a foetus?

Highly specialised and differentiated

Stem cells in plants

• Many stem cells in different parts of the plant

• Why it’s possible to make complete plants from small parts of the plant or just a few cells.

Why is cell specialisation important for the development and growth of a healthy egg from a fertilised cell?

• Babies need different types of cells

• As fertilised cell divides, cells specialise to form parts of the body

• Specialised cells undergo mitosis to further grow cells.

What cells cannot divide by mitosis?

Red blood cells and skin cells cannot divide by mitosis so stem cells replace dead or damaged cells.

Nerve cells don’t divide at all and aren’t replaced by stem cells so there aren’t replaced when damaged.

Where are stem cells found in plants?

Meristems, tip of root and stem

What happens in the meristems?

Mitosis takes place, cells elongate and grow before they finally differentiate once in their final position

What is unique about plant stem cell?

Once differentiated plant cells can re differentiate and become a completely different type of cell

Tatipotent

Stem cells that can turn into any other type fo cell

Multipotent

Stem cells that can only turn into a set cell type

What is therapeutic cloning

Clones embryos with same genetic makeup as patient which is used as the source of stem cells

Why is therapeutic cloning good?

• Genetically identical to patient

• Won’t be rejected b the patient’s immune system

• Fewer complications

Sources of embryonic stem cells

• Spare embryos left from fertility treatment

• Custom- made embryos with the embryo not being implanted, cloning

Use of plant stem cells?

• Produce clones of plants quickly

• Grow rarer plant species to prevent them from extinction

• Grow identical crops with desirable features

Ethical issues of using embryonic stem cells

• Question use of using potential humans as source of cells, violation of human rights

• Embryos cannot give any consent

• Embryo may get damaged

• Object to embryo being created and destroyed for purpose of therapeutic cloning

Religious issues of using embryonic stem cells

• Cannot accept any interference with the process of human reproduction

Disadvantage to using donor stem cells to treat a disease

• Not genetically identical to patient and may be rejected by immune system

Embryonic stem cells

Stem cells removed from an embryo which can differentiate into any cell

Social issues of stem cells

• Lack of understanding of what they are and how they can be used

• Whether benefits outweigh risks

• Research funded by companies and not peer reviewed

2 ways in which doctors can avoid the issue with using donor stem cells for treatment

• Using close family members stem cells

• Cells from donor that match closely to patient tissue type

adult stem cells

• Undifferentiated cells found in tissues where they can only differentiate into cells of that tissue

clinical issues of stem cells

• No guarantee of success

• Difficult to find suitable donors or embryonic stem cells

• Difficult to store embryonic stem cells

• Mutation can arise

• Risk of transfer of infections