STEM CELLS
What are stem cells?
Stem cells are the only cells able to divide themselves into different kinds of cells and their main function is to regenerate other dead cells, that's why they have many medical uses.
Stem cells are the only cells able to divide themselves into different kinds of cells and their main function is to regenerate other dead cells, that's why they have many medical uses.
TOTIPOTENT STEM CELLS: The ones able to form complete organisms.
PLURIPOTENT STEM CELLS: They can bacome any kind of organ maker cell, these are the embryonic stem cells.
MULTIPOTENT STEM CELLS: They can only form other cells of the same family.
UNIPOTENT STEM CELLS: They can only form one kind of cell.
PLURIPOTENT STEM CELLS: They can bacome any kind of organ maker cell, these are the embryonic stem cells.
MULTIPOTENT STEM CELLS: They can only form other cells of the same family.
UNIPOTENT STEM CELLS: They can only form one kind of cell.
PROBLEMS CAUSED BY EMBRYONIC STEM CELLS
The use of embryonic stem cells in medicine involves not only moral, but also a wide range of health problems. When scientists first started to study stem cells they realized that they could regenerate dead tissues by using them. But the first moral problem appeared, with the technology they had at that time they could only take embryonic stem cells from embyors, so they had to create an embryo in order to kill it and get the cells. Many conservative groups were against this method whic appeared to be effective but after some test it was proved that embryonic stem cells did not fit when they were put in other parts of the body and as it happens with organ transplants sometimes organisms rejected those cells.
After years of research scientists, discovered that they could turn medular cells into stem cells, so they could get cells from the patient to form embryonic stem cells and avoid them being rejected, but another problem appeared, those cells started growing as if they were in the uterus so they formed tumors.
After years of research scientists, discovered that they could turn medular cells into stem cells, so they could get cells from the patient to form embryonic stem cells and avoid them being rejected, but another problem appeared, those cells started growing as if they were in the uterus so they formed tumors.
CLONING
Cloning is to create asexually an identical organism to one that existed before basing on a copy of it's DNA, in other words to create a clon would be to reproduce artificially an identical organism. Clonation can happen naturally in some bacteria, funghi and a small number of plants, but when it comes to animals the process is much more complex and we cannot assure it's efficience.
DOLLY THE SHEEP
The most effective way of cloning known is the one used to create Dolly (the first mammal to be cloned), this process was based on mixing the DNA of an adult sheep and mixing it with some ovular cells that didn't have a nucleus. Despite this being the most succesful method, 277 embryos where needed to create dolly and the results were not as succesful as they expected, as appart from having the same cellular age as the original adult, Dolly suffered many problems. The conclusion was quite clear, it is possible to create an identical individual, but there is a high risk of it having health problems.
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CLONING VS EXTINCTION
Scientist from all over the world have always dreamed of cloning animals in danger of extinction or even animals that died out million years ago. There are some recent cases of cloning, but not all of them were succesful as it is really important to maintain the DNA in perfect conditions, a minimum change can ruin everything. That's what happened when some Australian researchers tried to clon the Tiger of Tasmania (extinct 65 years ago), that after years of investigation the cells conservation system failed and they couldn't keep on with the project.
There are even examples of this in famous Hollywood films as 'Jurassic Park', where a group of scientists took dinosaur DNA from mosquitos trapped in amber. This couldn't be possible since you need the DNA to be kept in perfect conditions. Some researchers tried to clon some mammoths using a similar method but it didn't work as the DNA sequences were uncomplete.
There are even examples of this in famous Hollywood films as 'Jurassic Park', where a group of scientists took dinosaur DNA from mosquitos trapped in amber. This couldn't be possible since you need the DNA to be kept in perfect conditions. Some researchers tried to clon some mammoths using a similar method but it didn't work as the DNA sequences were uncomplete.
HUMAN CLONING
Cloning in humans as some animal examples have shown is scientifically possible, however, there are some moral facts that put limits to it. Those moral troubles are principally religious because cloning breaks some 'laws' imposed by the church related to natural reproduction. Appart from this religious point of view, scientists see a principal problem, many of the animals previously cloned weren't totally healthy and there is always that risk of the human being born with some mental illness or disability. For that reason nowadays the only research on human cloning is about cloning embryonic stem cells to be able to reproduce organs for people who need transplants. The process would be the same used to clone animals like Dolly, but instead of creating a copy of the full organism, they copy tissues.