Download Emergent properties of cells and Stem Cells notes

Emergent Properties of Cells
• Emergent Properties
– Multicellular organisms
show emergent properties
– Emergent properties arise
from the interaction of
component parts
– In other words, the whole
is greater than the sum of
it’s parts
– The human eye is an
excellent example of this:
• Cells in multicellular organisms begin as stem cells
that are capable of expressing any of the genes they
contain and therefore performing any function for
the organism that they are a part of
• These stem cells will eventually differentiate to carry
out specialized functions for the organism
• This is done by “shutting off” certain genes while
allowing others to be expressed (“stay on”)
• Examples of cells that
have become
differentiated for
specific purposes
include red blood cells,
skin cells, brain cells,
muscle cells, and kidney
cells
• Stem cells are a major topic of modern day scientific
research
• Because they are undifferentiated they can be used
to replace any type of body cell needed
• For instance, in 2005, stem cells were used to restore
the insulation tissue(myelin) of neurons (brain cells)
in lab rats, resulting in subsequent improvements in
their mobility
• In humans, an example of the successful use of stem
cells is the treatment of Non-Hodgkins Lymphoma (a
type of cancer that destroys the lymphatic system)
– Cancer treatment such as radiation and
chemotherapy can destroy healthy red blood cells
along with the cancerous lymphatic cells
– Stem cells injected into patients can differentiate
to become healthy red blood
– Stem Cell Animation:
http://www.dnalc.org/stemcells.html
• Stem cell research can be quite controversial,
however, due to the ethical questions as to
how to obtain them
– Most commonly, stem cells are obtained
from embryos
• This can be of major concern for those
who feel that a life is being destroyed in
order to obtain the stem cells
How do we get stem cells?
• Embryonic Stem cells –
– Donated embryos from INVITRO fertilizations
– Allow fertilized egg to grow for roughly 5 days
– Egg is now Blastocyst – ball of approx. 100 cells
• Scientists remove cells from the inner cell mass of
the blastocyst and culture them in a petri dish with
nutrients and other growth factors.
• Blastocyst is destroyed while removing these cells
• Based upon the nutrients and growth factors these
cells can grow and reproduce indefinitely
Not just embryonic
• There are also “adult” stem cells called
somatic stem cells.
• These are cells found in animals that also can
be differentiated into a variety of cells.
– Hematopoietic stem cells – found in bone marrow
– Intestinal stem cells - small and large intestines
– Neural stem cells – can create new neurons
Therapuetic Cloning
– Therapuetic Cloning has been developed to use
already differentiated cells from a living person to
create stem cells:
• Take a healthy cell from patient
• Insert the nucleus of the healthy cell
(containing the patient’s DNA) with an egg cell
that has had it’s nucleus removed
• Egg cell divides multiple times to form a
blastocyst (hollow ball of cells) composed of
totipotent cells (capable of being pushed to
differentiate into any type of cell)
• Totipotent cells are pushed to differentiate
• Newly developed cells are injected into patient
• Not all cells are capable of becoming any cells.
• These are referred to as unipotent, or
pluripotent and are limited in the number of
types of cells they can differentiate to become