stem cells

When do humans start

When a sperm cell joins with an ovum(fertilisation)

What does the fertilise ovum undergo

Mitosis and forms a ball of cells called embryo.

What happens over time to cells in embryo

Continue to undergo mitosis.

Change and begin to form specialised cells

What is differentiation

Process by which unspecialised cells develop into specialised cells through particular adaptations

Cells in early embryo

Not differentiated

Any cell is capable of differentiating into any type of body cell

What is a stem cell

An undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells

2 types of stem cells

Embryonic stem cells

Adult stem cells

Where are adult stem cell found

Bone marrow

Adult stem cells differentiation

Can differentiate into cells found in our blood (red blood cell, white blood cell, platelets)

Ways stem cells are useful in medicine

Bone marrow transplant

Therapeutic cloning

What causes the need for bone marrow transplants

Leukaemia- cancer of the bone marrow

Bone marrow transplants

• patients existing bone marrow is destroyed by radiation

• Patients recieves a transplant of bone marrow from doctor

• Stem cells in bone marrow no divide to form new bone marrow and differentiate and form blood cells

2 problems with bone marrow transplant

• donor had to be compatible with patient, otherwise white blood cells produced by donated bone marrow may attack patients body

• Risk viruses can be passed from donor to patient

What is therapeutic cloning

An embryo is produced with the same gene as the patient

Psoitive of therapeutic cloning

System cels from embryo can be transplanted into patient without risk of rejection

Once inside patient, stem cells can differentiate to replace cells which have stopped working correctly

What is therapeutic cloning useful for

Medical conditions like diabetes or paralysis

Problems with therapeutic cloning

Ethical or religious objections to this procedure

What is stem cell in plants

Meristem tissue

What contains meristem tissue

Roots

Buds

What can meristem tissue do

Can differentiate into any type of plant tissue at any point in the life of the plant

How can we use meristem tissue

Stop a rare plant going extinct

Could produce cloned crop plants for farmers

Risks associated with the use of stem cells in medical treatment

Transfer of viral infections

Tumour formation

Rejection by immune system