Stem Cells

Review Greenhouse gases are a part of which cycle? A. CarbonB. NitrogenC. Phosphorus Which level is a plant in a food web? Who wrote evolutionary theory in his book On the Origin of the Species? Clownfish and the sea anemone live together. What type of relationship do they have? A. CommensalismB. MutualismC.Parasitism

Review Organelles are in which kind of cell? The organelle that digests cells parts and food is called what? What is the function of the nucleus? The cell doesn’t allow a virus to invade the cell. What stops it? A male is heterozygous dominant for a trait. What is his genotype?

Review A male with colorblindness marries a woman who is a carrier. What % of their children will possibly be colorblind? A. 0%B. 25%C. 50%D. 100% A black guinea pig and a white guinea pig have children that are grey. What type of dominance is this? Replicate the DNA: ATAGCCGAATAC

Stem Cells We have discussed cancer cells, now we are going to focus on stem cells Stem cells – unspecialized cells from which differentiated cells develop Differentiated cells – body cells which develop into specific types of cells Examples: blood, skeletal, muscle, heart, liver, kidney, brain, etc.

Adult Stem Cells Some cells must be constantly replaced (blood, skin, for example). These are replaced by stem cells. Blood stem cells are in bone marrow and skin cells are usually in the hair follicle Small portions of stem cells are in the brain, heart and skeletal muscle Multipotent – stem cells which can only replace certain types of cell (see above)

Embryonic Stem Cells Most stem cells are in fertilized egg or undeveloped baby (human babies, for example) Totipotent – cells which are literally able to do anything and can form any type of cell from these Pluripotent – cells that can develop into any of the body’s cell types but NOT in the tissue formed by the embryo

Human Development After about 4 days of development (yes, that is pretty fast) cells already know what to do Blastocyst – a hollow ball of cells which contain an inner cell mass This inner cell mass is pluripotent

Potential Benefits of Stem Cells Stem cells make it possible to develop a new field of regenerative medicine Undifferentiated stem cells are used to repair or replace damaged cells and tissues These can help in disorders such as Parkinson’s Disease, heart disease, stroke, macular degeneration, rheumatoid arthritis, spinal cord injuries and burns

Bad Things to Consider Adult stem cells take time to grow and there is no technology to grow these in large quantities Most stem cells come from aborted embryos The embryos are removed from the mother and stem cells are taken from them This is an ethical issue for a lot of folks and opens the door to controversy

Stem Cell Controversy Human embryonic stem cell research is controversial because the arguments for it and against it both involve ethical issues of life and death

But… Shinya Yamanaka of Kyoto University in Japan was able to convert human blastocyst cells into cells that closely resembled embryonic stem cells These are induced pluripotent stem cells This would eliminate need to “harvest” from embryos and they could be made