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