Download Stem cells - Dr Smith`s Biology Website

Stem cells + cell differentiation
HW task 2015
New
facts
Animal cell differentiation
After cell division most animal cells
differentiate and become specialised
cells.
Red blood cell
Neurone (nerve cell)
New
facts
• In animals most cell
differentiation happens
during embryo
development.
• In mature animals cell
division is mainly
restricted to making cells
for repair and
replacement (new cells
are not made for growth,
so mature animals do not
grow!).
New
facts
Plant cell differentiation
• Plant cells also differentiate to become
specialised cells.
Root hair cell
Mesophyll cell
(many chloroplasts for
photosynthesis)
(big surface area
to absorb water +
ions)
Xylem vessel
(hollow to
transport water +
ions)
New
facts
• However, many plant cells can
differentiate throughout their life so plants
are able to keep growing.
• Which parts of a
typical plant are
the main growing
regions?
• Which parts of a
typical plant are
the main growing
regions?
Shoot and root tips
(and buds)
New
facts
• Some differentiated
plant cells can redifferentiate and
become different
cells.
• This is used in plant
tissue culture to
clone identical plants.
To do
• Answer the questions in box 1 on the HW
sheet.
New
facts
Stem cells
Stem cells are unspecialized cells that can develop into any
type of cell. Unlike most cells, stem cells can divide unlimited
times.
stem cells
red blood cells
liver cells
muscle cells
New
facts
Stem cells and their uses
Watch the 3 videos from the website or via
these links
What are stem cells
http://youtu.be/evH0I7Coc54
What are stem cells (Bang goes the theory)
http://youtu.be/cEB8656TCIE
Watch the video clip “Building body parts
saving lives salamander style”.
http://youtu.be/eMHVRkwJ_R0
Stem cells may be used in
the future to:
a) grow replacement
organs for transplant (no
rejection problems if a
patients own stem cells
are used).
b) Treat people who are
paralysed. By injecting
stem cells into damaged
areas of the spinal cord,
new nerve and muscle
cells may form.
New
facts
To do
Answer the questions in box 2 on the
homework sheet
Stem cell ethics
• Many people object to the use of stem
cells for medical purposes.
• This is partly because embryos are the
best source of stem cells.
• You need to be able to argue the pros and
cons of using stem cells….
construct
+ apply
Using stem cells
Reasons for
• Best chance of cures for spinal
paralysis, diabetes,
Alzheimer's.
• Spare embryos used would be
destroyed anyway.
• Embryonic stem cells from
cord blood do not harm
anyone.
• Embryonic stem cells could
help grow new tissues and
organs for transplants.
Reasons against
• Embryonic stem cell research
is experimental and side
effects may include cancer.
• All embryos have the potential
to be a baby. Destroying them
is wrong.
• Embryo’s have a right to life
and cannot give permission to
be used, so its unethical.
• Money spent on stem cell
research would be better spent
on other medical approaches.
To do
• Answer the question in box 3 on the
homework sheet