stem cells

Embryonic stem cells

Humans start when a sperm cell joins with an ovum (egg cell)

The fertilised ovum now undergoes mitosis and forms a ball of cells called an embryo

Overtime these cells continue to undergo mitosis

They also change and begin to form specialised cells such as nerve cells and muscle cells

When cells specialise like this Scientists call this process differentiation

Cels in early stage embryo

Have not differentiated . Any cell is capable of differentiating into any type of body cell

A stem cell is an undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells

Adult stem cells

The stem cells in bone marrow differentiate to form cells found in our blood such as white blood cells platelets and red bloood cells

Bone marrow transplant

• leukaemia is a cancer of the bone marrow differentiate

• To treat this first the patients existing bone marrow is destroyed using radiation

• The patient then receives a transplant of bone marrow from a donor

• The stem cells in the bone marrow now divide and form new bone marrow . They also differentiate and form blood cells

Problems with bone marrow transplant

The donor has to be compatible with the patient . Otherwise the white blood cells produced by the donated bone marrow could attack the patients body

There is a risk that viruses can be passed from the donor to the patient

Stem cells can be used in therapeutic cloning

In this cloning an embryo is produced with the same genes as the patient

Stem cells from the embryo can be transplanted into the patient without being rejected by the patients immune system

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

Therapeutic cloning uses and other

This technique could be useful for a range of medical conditions such as diabetes or paralysis

Some ppl have ethical or religious objections to this procedure

Now stem cells in plants

Roots and buds contain meristem tissue . These stem cells can differentiate into any type of plant tissue at any point in the life of the plant

We could clone a rare plant to stop it from going extinct or we could produce cloned crops plants for farmers