Stem Cell Deffinations
- What are Stem Cells?:
- They are undifferentiated cells
- They can give rise to other types of cell
- There is no limit on the number of divisions it can do
- There are different types of stem cell: Pluripotent and Totipotent.
- Pluripotent Stem Cells can:
- Give rise to many different cell types
- Cannot give rise to embryonic cells
- Some of the genes have been deactivated.
- Totipotent Stem Cells can:
- Give rise to all 216 cell tyoes
- They are undifferentiated and unspecalised
- They can keep dividing
- All the genes have the potential to be active as no genes have been switched off.
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- How to stem cells become differentiated cells?
- A chemical stimulus is given to the unspecalised cells
- This causes some genes to be switched on and become active and genes to be switched off.
- mRNA is only made from active genes
- The mRNA moves to the ribosomes.
- The ribosomes read teh mRNA adn make the appropiate protein.
- The protein can pernanently alter the structure and function of the cells.
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Sources of Stem Cells
- Embryonic Stem Cells:
- Advantages --> Easy to extract and grow
- Disadvantages --> Ethical issues, possible rejection by patients body, risk of infection when cells recived, risk of stem cells becoming cancerous in body.
- Adult Stem Cells:
- Advantages --> Fewer ethical issues, rejection risk is avoided if stem cells are taken from the patient.
- Disadvantages --> Difficult to extract, more difficult to produce different cell types, risk of infection when cells are extracted or recieved.
- Fused Cells:
- A nucleus taken from the patients body cell is inserted into a human cell with the nucleus removed. It divides to produce stem cells with the patients DNA.
- Advantages -->Rejction risk avoided if nucleus is taken from the patient, there is a potential for treating genetic disorders.
- Disadvantages --> Ethical issues with the source of embryonic nuclei, risk of infection when cells recieved, risk of stem cells becoming cancerous in body.
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Risks with recieving stem cells
- Possible route to infection
- Rejected by patient
- Increased chance of the patient becoming cancerous
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