Download embryonic stem cells

Introducing stem cells
A life story…
Stem cells
cells that can
differentiate into a
variety of
specialized cell
types
What is a stem cell?
stem cell
SELF-RENEWAL
(copying)
stem cell
DIFFERENTIATION
(specializing)
specialized cell
e.g. muscle cell, nerve cell
What is a stem cell?
Stem cell
SELF-RENEWAL
(copying)
Identical stem cells
Stem cell
DIFFERENTIATION
(specializing)
Specialized cells
Why self-renew AND differentiate?
1 stem cell
1 stem cell
Self renewal - maintains
the stem cell pool
4 specialized cells
Differentiation - replaces dead or damaged
cells throughout your life
Where are stem cells found?
embryonic stem cells
blastocyst - a very early
embryo
tissue stem cells
fetus, baby and throughout life
Types of stem cells:
1) Embryonic stem cells
2) Tissue stem cells
Embryonic stem (ES) cells:
Where we find them
blastocyst
cells inside
= ‘inner cell mass’
embryonic stem cells taken from
the inner cell mass
outer layer of cells
= ‘trophectoderm’
fluid with nutrients
culture in the lab
to grow more cells
Stem cell jargon
Potency
A measure of how many types of specialized cells a stem cell
can make.
Pluripotent
Can make all types of specialized cells in the body
Embryonic stem cells are pluripotent.
Multipotent Can make multiple types of specialized cells, but not all types
Tissue stem cells are multipotent.
Embryonic stem (ES) cells:
What they can do
differentiation
embryonic stem cells
PLURIPOTENT
Embryonic stem cells are
exciting because they can
make all the different types
of cell in the body –
scientists say these cells are
pluripotent.
all possible types of specialized cells
Embryonic stem (ES) cells:
Challenges
skin
neurons
embryonic stem cells
blood
?
liver
Tissue stem cells:
Where we find them
surface of the eye
skin
testicles
brain
breast
intestines (gut)
bone marrow
muscles
Tissue stem cells:
What they can do
blood stem cell
differentiation
found in
bone marrow
MULTIPOTENT
only specialized types of blood cell:
red blood cells, white blood cells,
platelets
Tissue stem cells can ONLY make the kinds of cell found in the tissue they belong to.
So, blood stem cells can only make the different kinds of cell found in the blood.
Brain stem cells can only make different types of brain cell. Muscle stem cells can
only make muscle cells. And so forth.
http://www.youtube.com/watch?v=2-3J6JGN-_Y#t=36
Cell Differentiation
Cell differentiation – process of
converting stem cells into more
specialized cell types in
multicellular organisms
 Examples: muscle cells, liver
cell, red blood cells
When does cell differentiation occur?
oDevelopment of a zygote into a full
organism
oTissue repair
oNormal cell turnover
•All of these require the repeated division and
differentiation of stem cells.
What is gene expression?
Gene expression is the
activation of a gene
that results in a
protein & is a very
controlled regulated
process.
Why are all our cells different?
•They EXPRESS different
portions of the genetic code
(genes).
•This means that different
proteins are made by
different cells causing them
to look and function
differently.
How does Gene Expression make our body cells
different?
•Every cell in our
body has the same
30,000 genes, but
each cell selectively
activates (“turns
on”) certain genes
•The information on DNA
(activated genes – those that
are “turned on”) is translated
into an organism's traits by
producing specific
proteins.
Protein
•Environmental
factors such as
temperature, pH, and availability of
nutrients can influence the genes
expressed in a cell.
•Genes + Environment = Trait
Himalayan Rabbits
•If a small section of
fur is shaved from a
Himalayan Rabbit,
the fur will grow back
either white or black
depending on the
temperature of its
environment .
HOT
COLD
Hydrangea
• How does the environment
affect hydrangea growth?
• Depending on the pH of the
soil, Hydrangea can range in
color from blue to pink.
•All
the cells in our body
have the exact same DNA
because they all came
from a single cell which
replicated its DNA
•Although
every cell in
your body has the same
DNA, not all cells are the
SAME. Why?