Stem cells

https://www.revisely.com/gcse/biology/aqa/video/zZx

What is fertilisation

Humans start when a sperm cell joins with an ovum (egg cell) this is called fertilisation.

After the fertilised ovum undergoes mitosis, what will it form.

A ball of cells called an embryo, and overtime these cells continue to undergo mitosis.

What do embryos do.

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

When cells specialise like this, what do scientists call it.

They call this process differentiation.

What is a stem cell

an undifferentiated cell that has the potential to develop into different specialized cell types

How do bone marrow transplants work.

Leukaemia is a cancer of bone marrow.

To treat it, patient’s existing bone marrow destroyed using radiation.

They then receive a transplant of bone marrow from donor.

The stem cells in bone marrow divide and form new bone marrow.

They also differentiate and form blood cells.

What are 2 problems of a bone marrow transplant.

The donor has to be compatible with the patient otherwise the white blood cells produces 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.

What is therapeutic cloning.

In therapeutic cloning, an embryo is produced with the same genes as the patient.

This is so Stem cells from embryo transplanted into patient wont be rejected by patient’s immune system.

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

Could be useful for diabetes or paralysis

What do roots and bud contain, and what do they do.

Meristem tissues, they are stem cells that can differentiate into any type of plant tissue at any point in the life of the plant..