All living things are made of cells Cells can specialize into different cell types Cells tissues organs These cells tissues and organs make up the systems of an organism How ID: 1042369
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1. Cell SpecializationRemember . . . . .All living things are made of cells!!!Cells can specialize into different cell types Cells tissues organs These cells, tissues, and organs make up the systems of an organismHow do cells know what job they have to do? What tissue they will belong to?How do cells become specialized?
2. Stem CellsStem cells – unspecialized cells that can differentiate into a variety of specialized cells Embryonic stem cells Adult (tissue) stem cells Differentiation – process of converting stem cells into more specialized cellCells have specific structure and functionOccurs when a zygote becomes an organismFor tissue repairNormal cell renewal (self-renewal)Ex. liver cell, blood cell, nervous cell,Muscle cells, bone cell
3. Stem Cell Vocabulary and DevelopmentTotipotent – fertilized egg or first few cells in an embryo that are able to form any kind cell and tissuePluripotent – cells in the embryonic blastocyst (hollow ball of cells) stage can become any type of body cellMultipotent – adult stem cells that can produce certain differentiated cellsA stem cell that can:Become any type of cell in the body is pluripotentBecome only a few type of cells is multipotent
4. Why are Stem Cells so Special?When a stem cell divides, it can either:Self-renew – make more stem cellsSpecialize and make other cell types
5. Embryonic stem cells – cells harvested from an embryo (blastocyst stage)Can become any cell typeCan reproduce indefinitelyUsually created from in vitro fertilizationControversialType of stem cell
6. Adult stem cell - can renew itself and can differentiate to yield some or all of the major specialized cell types of the tissue or organ they came frommaintain and repair the tissue in which they are foundHave been used for blood-formingstem cells from bone marrow have been used in transplants for more than 40 yearsScientists now have evidence that stem cells exist in the brain and the heart, two locations where adult stem cells were not at first expected to reside. If the differentiation of adult stem cells can be controlled in the laboratory, these cells may become the basis of transplantation-based therapies.
7. All cells contain the exact same DNA (all 46 chromosomes), but not all cells look the same nor have the same jobDifferent proteins are madeby different cells causing them to look and functiondifferentlyCalled gene expressionControlled by signals received from control genes, enhancers, or promoter genes “turning on” certain sequences of DNA (a gene)
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