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. Cultured embryonic stem cells
Differentiation of embryonic stem cells in culture
Liver cells
Cultured embryonic stem cells
Nerve cells
Heart muscle cells
Different culture conditions
Different types of differentiated cells
Figure 11.5

7. Stem Cells Donor cell Nucleus from donor cell
Implant blastocyst in surrogate mother
Clone of donor is born (REPRODUCTIVE cloning)
Remove nucleus from egg cell
Add somatic cell from adult donor
Grow in culture to produce an early embryo (blastocyst)
Remove embryonic stem cells from blastocyst and grow in culture
Induce stem cells to form specialized cells for THERAPEUTIC use

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

10. How to Clone Tadpole (frog larva) Frog egg cell Nucleus UV
Intestinal cell
Nucleus
Transplantation of nucleus
Nucleus destroyed
Tadpole
Eight-cell embryo

11. 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.
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12. Dolly, the first cloned sheep, with her lamb
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13. Click to view animation.
Cloning of Dolly
Click to view animation.