Stem Cells Characteristics They continue to grow and proliferate,
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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 typeA pluripotent stem cell can form most or all of the 210 differentiated cell types in the adult bodyA 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 CellsSkin, Sperm, Fat, BoneEmbryonal 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 tissueThis 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 laboratoryHard to form the desired specific cell type in the culture dish.Could form tumors in patientsOnly scant evidence that embryonic stem cells can actually work in the body
6 Cultured embryonic stem cells Differentiation of embryonic stem cells in cultureLiver cellsCultured embryonic stem cellsNerve cellsHeart muscle cellsDifferent culture conditionsDifferent types of differentiated cellsFigure 11.5
7 Stem Cells Donor cell Nucleus from donor cell Implant blastocyst in surrogate motherClone of donor is born (REPRODUCTIVE cloning)Remove nucleus from egg cellAdd somatic cell from adult donorGrow in culture to produce an early embryo (blastocyst)Remove embryonic stem cells from blastocyst and grow in cultureInduce stem cells to form specialized cells for THERAPEUTIC use
8 CloningCloning means to make an identical copy of something, including copying DNACloning a new organism from a pre-existing one is known as asexual reproduction because it does not involve sex
10 How to Clone Tadpole (frog larva) Frog egg cell Nucleus UV Intestinal cellNucleusTransplantation of nucleusNucleus destroyedTadpoleEight-cell embryo
11 Micropipette about to penetrate unfertilized sheep egg to remove nucleus Egg has been emptied of its nucleus, which holds DNADNA from donor cell is about to enter the enucleated egg. A spark will stimulate cell divisions.Do not post to Internet
12 Dolly, the first cloned sheep, with her lamb Do not post to Internet
13 Click to view animation. Cloning of DollyClick to view animation.