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Stem cell research Bryan Spiegelberg bspiegel@gac.edu http://homepages.gac.edu/~bspiegel/ x7651
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True/False President Bush declared research on embryonic stem cells illegal in the U.S.
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True/False Embryonic stem cell research is not funded by Federal money
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True/False President Bush created new restrictions on the use of Federal funds for embryonic stem cell research.
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True/False The widespread use of stem cells in medical treatments is a long way off.
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True/False The widespread use of embryonic stem cells in medical treatments is a long way off.
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True/False Most major religions officially oppose research on embryonic stem cells.
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True/False It is necessary to destroy an embryo to obtain embryonic stem cells.
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True/False Embryonic stem cell research might lead to human cloning.
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“Cloning” Production of multiple genetically identical organisms
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True/False Routine cloning of organisms is stuff of science fiction.
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True/False OK, but higher organisms can’t be cloned.
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Dolly (1996-2003): genetically identical to her adult mother Since: mice, cats, pigs, cattle, rats…no primates, yet…
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True/False No human clones exist.
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True/False Most Americans support research on embryonic stem cells
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ABC News poll: Legality of stem cell research: 58% pro/30% con Funding SCR: 60% pro/31% con
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International Communications Research (ICR) poll Support stem cell research if it means an embryo is destroyed? 24% pro/70% con
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CYTOPLASM -energy production -biomolecule factories -etc. NUCLEUS -genetic material: information storage -info helps define cell’s characteristics shape, rate of growth, etc.
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Nucleus/Genetic information –Link between a cell and its ancestor Information: DNA → book chromosomes → chapters genes → words
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DNA vs. Proteins Words → don’t mean much without action PROTEINS → main actors derived from and taking direction from the DNA Individuality derives ultimately from the DNA
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Cells → Tissues → Organs → Organisms ~10-100 trillion (10 14 ) total cells in your average human ~200 types of specialized cells Blood cells Neuron
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Blood cells/neurons, etc. are terminally differentiated (a.k.a. post-mitotic) –Typically stop dividing/growing Focus on specialty –When lost → damage/old age Often need to be replaced: How? “Like” cells dividing OR Stem cell progenitors ADULT Stem Cells: Why?
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STEM CELL Undifferentiated Cell division TWO DAUGHTER CELLS Two different fates 1.UNDIFFERENTIATED Self-renewal 2.DIFFERENTIATED Replace lost cell
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Stem cells by definition 1.Non-terminally differentiated cell that can give rise to specialized cells 2.Able to divide without limit 3.Self-renewal: Undergo asymmetric cell division
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A: Stem cell B: Progenitor cell C: Specialized cell
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Single cell → Fertilized egg/zygote 10 trillion adult cells PROLIFERATION 200 specialized types of cells SPECIALIZATION EMBRYONIC Stem Cells: What? Why?
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+ FERTILIZED EGG Is it “human”? Nervous system Skin cells Germ cells Placenta etc. Founding cell must be a totipotent stem cell
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Totipotent: unlimited potency Able to generate all cells of the developing organism: placenta, somatic cells, germ line Pluripotent: some loss of potency eg. potential progenitor of somatic cells, germ line, but not the placenta Multipotent: limited potency only generate related specialized cells eg. hematopoietic stem cells differentiate into red/white blood cells, platelets, etc. Unipotent: generate a single type of cell (but still self-renewing)
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Development ZYGOTE MORULA BLASTOCYST (internal cavity) 2-3 days in mice
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Blastocyst INNER CELL MASS toti/pluripotent TROPHECTODERM placenta UTERINE WALL mom BLASTOCOEL
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Inner cell mass: highly potent Formation of a teratoma upon injection –“monster tumor” –disorganized differentiation upon implantation Skin, bones, glandular tissues, hair, etc.
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