AS EDEXCEL 3.3 STEM CELL REVISION NOTES

Whole chpater covered in a few simple bullet points outlining advantages and disadvantages of stem cell therapy . 

key terms and process of therapeautic cloning .

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  • Created on: 14-01-13 20:09
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3.3 Stem cells and beyond
2 defining features of stem cells
1. Potency ­ ability to differentiate into cell types
2. Self renewal ­ divide continuously in an unspecialised state
EMBYONIC STEM CELLS
Earliest embryonic cells are totipotent (stem cells which can differentiate into all types of cells ). By
the Blastocyst stage the embryo would implant into the mothers uterus, the inner cells of this ball are
pluripotent (have the potential to be any type of cell except for the placenta ).
Embryonic stem cells are totipotent which can differentiate into at least 200 different cell
types
Ethical issues- embryonic stem cell process requires embryos to be destroyed , this is a great
disadvantage as people think it is morally wrong to kill life
UMBILICAL CORD STEM CELLS
The blood that drains from the placenta and umbilical cord is a rich source of pluripotent stem
cells. The blood can be frozen and stored which can used later on in life if the child or family is
in need of it .
However, problems such as storage space make it an issue as do to it for a great population
would require a huge amount of space and would be very costly.
ADULT STEM CELLS (somatic stem cells)
Initially, Adult stem cells are multipotent as they have the ability to differentiate into limited
number of cells.
Problems with Adult stem cells
It is difficult to culture adult stem cells because huge cultures are needed for stem cell
therapy. Also , triggers are needed to be found to persuade stem cells to differentiate into
specific cell types
Bone marrow transplant are given by a closely matched donor usually a relative otherwise
the body's immune system will reject it
There are no ethical issues with adult stem cells as when taken the person would face no harm as the
bone marrow will continue to regenerate cells .
STEM CELL CLONING / THREAUPITIC CLONING

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ADVANTAGES OF STEM DISADVANTAGES OF STEM
CELL THERAPY CELL THERAPY
Tailor made cells to replaceIt can cause cancers to
damaged ones would develop this is evident in
revolutionise medicine. people who have had bone
marrow transplant
Glycoprotein on the However, the immune system
surface of your cell can attack the transplanted
membranes act as a part of organ. But with the help of
your cell recognition immunosuppressant drugs the
system, advantage is you immune system gradually
pick up an infection .one accepts it.…read more

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Donated cells are identical
so there are no problems
with rejection
WHO COULD BENIFIT FROM STEM CELL THERAPY
PARKISONS DISEASE
Brain disorder affecting people over 65yrs old
Nerve cells that produce dopamine stop working , as dopamine levels fall , people develop
uncontrollable tremors in their body . Leading to their body not being able to move properly
With the use of stem cells it is initiated that stem cell transplants will allow to replace the lost
brain cells and restore dopamine production.…read more

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