1 Stem Cells

2 What are Stem Cells? Stem Cells: Cells that can turn into specific types of cells (neurons, skin cells, etc.) Adult: held somewhere in body; replace skin, intestinal, and blood cells Embryonic: come from fertilized eggs

3 Adult Stem Cells Multipotent: can become only a few cell typesReplace constantly dying cells (skin, intestines, blood) Scientists are able to turn adult stem cells into embryonic stem cells by inserting genes into them! This became necessary when embryonic stem cell research was banned in 2000

4 Embryonic Stem Cells Totipotent: “The Mother of All Stem Cells”- Can give rise to any cell type - Fertilized egg or a few divisions later Pluripotent: “Stem Cell Lines” - Can give rise to 200 cell types - Blastocyst (Day 4 after fertilization) - Stem Cell Lines come from unused blastocysts from In-Vitro procedures

5 Day 1 Fertilized Egg: TotipotentDay 4 Blastocyst: Pluripotent

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8 Potential Uses of Stem CellsDrug Testing: Grow liver cells to test the effects of a drug on the liver, for ex. Research how genes are turned on and turned into organs, etc. Prevent cancer, birth defects

9 U.S. Battle over Stem Cells2000: Gov’t. begins to only fund research on existing stem cell lines 2004: House passes bill to fund research with new stem cell lines; Bush vetoes 2007: House and Senate pass bill to fund research again; Bush vetoes 2009: Obama overturns 2000 decision