Zusammenfassung der Ressource
B1 cells - stem cells
- embryonic stem cells can turn into ANY type of cell
- differentiation is the process by which a cell changes
to become specialised for its job
- undifferentiated cells, called stem cells. can divide to produce
lots more undifferentiated cells
- they can differentiate into different types
of cells. depending on what instructions
they're given.
- stem cells are found in early human embryos. They're
exciting to doctors and medical researchers because they
have the potential to turn into any kind of cell.
- this makes sense if you think about it - ALL the
different types of cell found in a human being have to
come from those few cells in the early embryos
- adults also have stem cells, but they're only found in certain
places, like bone marrow. Unlike embryonic stem cells, they
CAN'T turn into any cell type, only certain ones
- stem cells from embryos and bone marrow can be grown in a
lab to produce clones and made to differentiate into
specialised cells to use in medicine or research
- stem cells may be able to cure many diseases
- medicine already uses adult stem cells to cure disease
- EXAMPLE - stem cells transferred from the bone
marrow of a healthy person can replace faulty
blood cells in the patient who receives them.
- embryonic stem cells could also be used to replace faulty cells
in a sick person
- you could make insulin - producing cells for people
with diabetes, nerve cells for people paralysed by
spinal chords
- in a type of cloning, called therapeutic cloning, an embryo
could be made to have the same genetic information as
the patient. This means that the stem cells produced
would also have the same genes and so wouldn't be
rejected by the patient's body if used to replace faulty
cells
- however, there are risks involved in using stem cells in
medicine
- EXAMPLE- stem cells grown in the lab, may
become contaminated with a virus which could
be passed on to the patient and so make them
sicker,
- some people are against stem cell research
- some people are against stem cell research because they fell
that human embryos shouldn't be used for experiments since
each one is a potential human life
- others think that curing
existing patients who are
suffering is more important
than the rights of embryos
- one fairly convincing argument for this point of view is that the embryos used
in the research are usually unwanted ones from fertility clinics which, if they
weren't used for research, would probably just be destroyed. But of course,
campaigners for the rights of the embryos want this banned too.
- these campaigners fell that scientists
should concentrate more on finding and
developing other sources of stem cells,
sop people could be helped without
having to use embryos
- in some countries stem cell research is banned
- it's allowed in the UK as long as it follows strict guidelines
- stem cells can produce identical plants
- in plants, stem cells are found in the meristems (parts of the plant
where growth occurs)
- throughout the plant's entire life, cells in the meristem tissue can
differentiate into any type of plant cell.
- these stem cells can be used to produce clones
of whole plants quickly and cheaply
- they can be used to grow more plants of rare
species (to prevent them being wiped out)
- stem cells can also be used to grow crops of
identical plants that have desired features for
farmers e.g disease resistance