Emergent Properties of Cells Emergent Properties Multicellular organisms

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 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