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B2 - Cell division (Stem cell dilemmas (Ethical issues behind using an…
B2 - Cell division
Stem cell dilemmas
Ethical issues behind using an embryo as a source of cells, when potentially it could've been a human, some see it as alive
Scientists have resolved this concern by using amniotic fluid or the blood from the umbilical cord, which both contain stem cells
Embryotic stem cells are hard to control, difficult to specialise and expensive
Because embryotic stem cells divide so rapidly, they could cause cancer
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Therapeutic cloning takes cells from an adult to produce a genetically identical embryo, so cells won't be rejected
Cell division
You have 46 chromosomes in the nucleus of your body cells - 23 pairs, inherit half from each parent
Body cells divide by mitosis, producing 2 genetically identical cells, to allow your body to grow as well as replace damaged cells
The cell cycle:
- Cell grows bigger and duplicates its DNA to form two copies of each chromosome, produce more sub-cellular structures
- The two sets of chromosomes are pulled to opposite ends of the cell and the nucleus divides
- The cytoplasm divides, forming two cells
Mitosis happens rapidly up until puberty, when it slows
Differentation
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In animals, there is not much cell division when the animal is an adult, however in plants cells continue to differentiate throughout their lives
In plants, undifferentiated cells are formed at meristems (stems and roots)
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It is easier to clone plants that animals because a single plant cell can under-go mitosis and differentiate into xylem, phloem ect…, where as differentiation in animal cell is permanent, and a specialised cell can only produce more of that cell
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Stem cells
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We could grown new organs from stem cells, or produce cells which cure diabetes or make someone who is paralysed walk again
Plant stem cells can be used to a grow large number of plants quickly and economically, they can be used to bring back plant species which are going extinct, or to clone plants with special qualities for agriculture e.g disease resistance