Every cell in your body is gentically identical. Through the process of __________, cells have different genes 'switched on or off'. The become different in structure because they produce different proteins.
Most cells have a limit to the number of divisions they undergo, the __________ limit.
At the embryo stage of development there special cells known as __________ cells. They can differentiate into all other types of cells, but that cells lose this ability as the animal __________.
__________ cells and __________ cells have no Hayflick limit.
Stem cell therapy could lead to treatments in which __________ cells are replaced with those grown from stem cells. This research is controversial as stem cells have to be harvested from unwant IVF blastocysts which some people beleive are living beings.