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Stem Cells

Stem Cells. Characteristics They continue to grow and proliferate, Given the correct signals (from a hormone or a ‘growth factor’) they can differentiate into a particular specialized cell type. Some stem cells have more abilities than others.

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Stem Cells

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  1. Stem Cells • Characteristics • They continue to grow and proliferate, • Given the correct signals (from a hormone or a ‘growth factor’) they can differentiate into a particular specialized cell type

  2. Some stem cells have more abilities than others • A unipotent stem cell can form only one differentiated cell type • A pluripotent stem cell can form most or all of the 210 differentiated cell types in the adult body • A totipotent stem cell can form not only adult cell types, but also the specialized tissues needed for development.

  3. Where do we get stem cells? • Adult Stem Cells • Skin, Sperm, Fat, Bone • Embryonal Carcinoma Cells(EC cell) • Embryonic Stem Cells (ES cell) • Embryonic Germ Cells (EG cell)

  4. Embryonic Stem Cells • Hope • A lot of cells can be grown and then given hormonal signals to specialize into a specific tissue • This could be used to create new cells or tissue on demand and treat illnesses such as diabetes, Alzheimer’s and spinal cord injuries

  5. Embryonic Stem Cells • Problems • Inefficient to get them to start growing and keep growing in the laboratory • Hard to form the desired specific cell type in the culture dish. • Could form tumors in patients • Only scant evidence that embryonic stem cells can actually work in the body

  6. Differentiation of embryonic stem cells in culture Liver cells Culturedembryonicstem cells Nerve cells Heart muscle cells Different cultureconditions Different types ofdifferentiated cells Figure 11.5

  7. Stem Cells Donorcell Nucleus fromdonor cell Implant blastocystin surrogate mother Clone of donoris born(REPRODUCTIVEcloning) Removenucleusfrom eggcell Add somaticcell fromadult donor Grow in culture to producean early embryo (blastocyst) Remove embryonic stem cells from blastocyst andgrow in culture Induce stemcells to formspecialized cellsfor THERAPEUTICuse

  8. Cloning • Cloning means to make an identical copy of something, including copying DNA • Cloning a new organism from a pre-existing one is known as asexual reproduction because it does not involve sex

  9. How to Clone Tadpole (frog larva) Frog egg cell Nucleus UV Intestinal cell Nucleus Transplantationof nucleus Nucleusdestroyed Tadpole Eight-cellembryo

  10. Micropipette about to penetrate unfertilized sheep egg to remove nucleus Egg has been emptied of its nucleus, which holds DNA DNA from donor cell is about to enter the enucleated egg. A spark will stimulate cell divisions. Do not post to Internet

  11. Dolly, the first cloned sheep, with her lamb Do not post to Internet

  12. Cloning of Dolly Click to view animation.

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