What are stem cells?
How?
What are the different categories of stem cells?
Undifferentiated cells that continually divide to become specialized.
- differentiation is the process by which stem cells become specialised
Totipotent,pluripotent,multipotent,unipotent (all have different differentiation abilities.
What is a totipotent stem cell?
How do they differentiate?
When do they occur?
Stem cells that can divide and produce any type of body cell
(During development) Translate only part of their DNA, resulting in cell specialization.
For a very limited time in mammalian embryos.
What are pluripotent stem cells?
What are they used for?
What are the issues surrounding pluripotent cells?
Stem cells that are found in embryos and can differentiate into almost any type of cell
Used in research with prospect of treating human disorders (may be used to regrow damaged cels in humans; replace burnt skin cells, beta cells for diabetes t1, neurons for parkinsons)
Sometimes treatment doesn’t work or stem cells continually divide to make tumors
-ethical debate on whether its ok to make therapeutic clone of yourself to make an embryo to farm stem cells to cure a disease, then destroy the embryo
What are multipotent/ unipotent cells?
What is the difference between multipotent and unipotent cells?
Both are found in mature mammalia
-can divide to form limited number of different cell types
Multipotent cells (e.g bone marrow) can differentiate into a limited number of cells
Unipotent cells can only differentiate into one type of cell (e.g heart muscle cells)
What is the source of :
pluripotent cells?
Multipotent cells?
Embryos, up to 16 days of fertilization contain stem cells that are pluripotent and can differentiate into any type of cell.
Umbilical cord blood contains stem cells which are multipotent, like adult stem cells
-placenta also has stem cells that are multipotent
-adult stem cells (e.g bone marrow) also has multipotent cells
What are iPS?
How are they produced? Why do we use them?
Induced pluripotent cells
Produced from adult somatic (any diploid body cell) using appropriate protein transcription factors (to overcome some ethical issues using embryonic stem cells)
Explain fully how iPS cells are produced.
How is this ethical?
Why are iPS cells so useful?
Created from adult unipotent cells (almost any body cell is altered in the lab to return them to a state of pluripotency. This happens by turning the genes that were switched off to make the cell specialised back on using transcriptional factors (these activate the genes)
Do not cause the destruction of and embryo and the adult patient can give permission.
Shown self renewal property, can divide indefinitely to give limitless supplies (so may be used instead of embryonic stem cells)
