Haretha Aydi
Access I.T
Human Cloning Assignment
Introduction:
In this assignment, we are to choose a specific subject and write out and argument with and against it. We should also include background information and carry out a research on that specific topic, lastly a conclusion should be set out.
Background Knowledge:
)- Human cloning:
First explored by Spemann in the 1920's to conduct genetics research, nuclear transfer is the technique currently used in the cloning of adult animals. A technique known as twinning exists, but can only be used before organism's cells differentiate. All cloning experiments of adult mammals have used a variation of nuclear transfer.
Nuclear transfer requires two cells, a donor cell and an oocyte, or egg cell. Research has proven that the egg cell works best if it is unfertilized, because it is more likely to accept the donor nucleus as its own. The egg cell must be enucleated.
The nucleus is removed from the egg cell This eliminates the majority of its genetic information. The donor cell is then forced into the Gap Zero, or G0 cell stage, a dormant phase, in different ways depending on the technique. This dormant phase causes the cell to shut down but not die. In this state, the nucleus is ready to be accepted by the egg cell. The donor cells nucleus is then placed inside the egg cell, either through cell fusion or transplantation. The egg cell is then prompted to begin forming an embryo. then, the embryo is then transplanted into a surrogate mother. If all is done correctly, occasionally a perfect replica of the donor animal will be born.
Each group of researchers has its own specific technique. The best known is the Roslin technique, and the most effective and most recently developed is the Honolulu technique.
The cloning of Dolly has been the most important event in cloning history. Not only did it spark public interest in the subject, but it also proved that the cloning of adult animals could be accomplished. Previously, it was not known if an adult nucleus was still able to produce a completely new animal. Genetic damage and the simple deactivation of genes in cells were both considered possibly irreversible.
The realization that this was not the case came after the discovery by Ian Wilmut and Keith Cambell of a method with which to synchronize the cell cycles of the donor cell and the egg cell. Without synchronized cell cycles, the nucleus would not be in the correct state for the embryo to accept it. Somehow the donor cell had to be forced into the Gap Zero, or G0 cell stage, or the dormant cell stage.
First, a cell (the donor cell) was selected from the udder cells of a Finn Dorset sheep to provide the genetic information for the clone. For this experiment, the researchers allowed the cell to divide and form a culture in vitro, or outside of an animal. This produced multiple copies of the same nucleus. This step only becomes useful when the DNA is altered, such as in the case of Polly, because then the changes can be studied to make sure that they have taken effect.
The donor cell is grown in a petri/culture dish.
A donor cell was taken from the culture and then starved in a mixture which had only enough nutrients to keep the cell alive.
This culture dish barely has enough nutrients to keep the cell alive.
This caused the cell to begin shutting down all active genes and enter the G0 stage. The egg cell of a Blackface ewe was then enucleated and placed next to the donor cell. One to eight hours after the removal of the egg cell, an electric pulse was used to fuse the two cells together and, at the same time, activate the development of an embryo.
The enucleated egg cell and the mammary cell are fusing together.
This technique for replicates the activation provided by sperm is not completely correct, since only a few electrically activated cells survive long enough to produce an embryo.
If the embryo survives, it is allowed to grow for about six days, incubating in a sheep's oviduct. It has been found that cells placed in oviducts early in their development are much more likely to survive than those incubated in the lab. Finally, the embryo is placed into the uterus of a surrogate mother ewe. ...
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The enucleated egg cell and the mammary cell are fusing together.
This technique for replicates the activation provided by sperm is not completely correct, since only a few electrically activated cells survive long enough to produce an embryo.
If the embryo survives, it is allowed to grow for about six days, incubating in a sheep's oviduct. It has been found that cells placed in oviducts early in their development are much more likely to survive than those incubated in the lab. Finally, the embryo is placed into the uterus of a surrogate mother ewe. That ewe then carries the clone until it is ready to give birth. Assuming nothing goes wrong, an exact copy of the donor animal is born.
This newborn sheep has all of the same characteristics of a normal newborn sheep. It has yet to be seen if any adverse effects, such as a higher risk of cancer or other genetic diseases that occur with the gradual damage to DNA over time, are present in Dolly or other animals cloned with this method.
What it needs in three steps.
- The DNA to be copied is dissolved in buffer and mixed with a pair of primers, which are short lengths of single-stranded DNA complimentry to the end of the DNA strand.
- The four deoxynucleotide triphosphates Adenine, guanine, cytosine, or thymine attached to deoxyribose and three phosphates.
- A heat stable DNA polymerase obtained from the thermophilic bacterium Thermus aquaticus.
PCR is so sensitive that it can be used to trace the presence of bacteria on one molecule before there are sufficient numbers for the bacteria to produce symtoms; useful for testing HIV.
2)- Gene therapy:
Gene therapy by gene supplementation in somatic cells may help those suffering from genetic conditions such as cystic fibrosis. Although a mutant gene occurs in all cells of the body only those tissues particularly affected (where the gene is switched on) by the mutant gene would be targeted for therapy, i.e. the lungs of a cystic fibrosis sufferer, blood cells in the bone marrow in ß thalassaemia and the muscles in Duchemme muscular dystrophy.
As cells eventually die, so do the tissues being treated by the gene therapy therefore the treatments have to be repeated.
To carry out gene therapy DNA must be entered into the nucleus of the cells. This can be carried out using a number of vectors. Microinjection is the use of a fine needle to inject DNA into the nucleus; electroporation is an electric pulse causing temporary holes in the membrane allowing the fine DNA strands to enter the cell. Viruses can also be used to inject DNA into the nucleus of the cell. The virus can be genetically engineered to remove genes that allow it to multiply and cause disease.
In some conditions there is a gene that must be removed or neutralized, this is known as a "gain of function" disorder. Gene supplementation is proving to be a possible solution for some "loss of function" conditions such as Cystic Fibrosis where a gene is missing. In the case of Cystic Fibrosis an aerosol inhaler is being developed which will allow sufferers to take in the missing gene into the lungs by inhaling artificially formed spheres known as liposome. The DNA is carried within the liposome which fuses with cells allowing the DNA they contain to enter the cell. This treatment does not however help with the pancreatic problems.
An example of effective gene supplementation is to treat Severe Combined Immune-deficiency Disease (SCID). The gene coding for adenosine de-aminase is mutated and homozygotes are unable to de-aminate adenosine. This leads to the death of lymphocytes therefore the sufferer has no immune system. In an experiment some of the lymphocyte precursor cells in the bone marrow were infected with a virus carrying the missing gene. The treatment must be repeated every month as the lymphocytes have a life span of only a month.
3)- Human Hormones:
Human Growth Hormone is a peptide hormone like insulin, produced in the anterior pituitary gland. If there is a change in the genetic code the hormone produced is different and doesn't work correctly. Human growth hormone is only active in humans therefore a hormone from another species cannot be used in it's place, as in the previous treatment for diabetes when insulin was not produced. Human Growth Hormone causes cells to grow and multiply by directly increasing the rate at which amino acids enter cells and are built into proteins. Human Growth Hormone deficiency results in dwarfism and the condition can only be treated if recognised in the early teens, before the bone plates close. Treatment is by supplementation of the hormone. In the past the hormone was removed from the pituitary glands of dead people and was then injected into people suffering from lack of the hormone.
Nowadays genetic engineers can produce Human Growth Hormone in a similar way to the production of insulin, the gene is introduced into bacteria DNA such as E. Coli and the bacteria multiply to produce a yield of the hormone, which can then be injected into sufferers to replace the missing gene.
Factor VIII is cloned for elimination of viral infections from blood transfusions in light of the AIDS epidemic. Factor VIII is also one of the proteins involved in blood clotting and is deficient in a group of haemophiliacs - sufferers of Haemophilia VIII. By introducing the correct gene for Factor VIII there is a greater chance of haemophiliac's blood clotting and therefore the risk of bleeding to death is reduced, as the protein to form blood clots will be manufactured in cells.
Discussion:
The practice of cloning can be used to benefit society and therefore should be legalized. Ever since the cloning of the first adult sheep, Dolly, the idea of cloning has become a major issue and the subject of many debates. Many people are afraid of the idea of cloning because it is new and misunderstood.
There is the notion that a clone would not be the same as any other person, but a clone is just a normal person, created with and having the same genes as the person being cloned. A clone will not be exactly the same as the original person. Because they will not have the same environment and experiences as the person from which they were cloned, a clone is more like a younger identical twin with a personality all of its own. There are also differences in mitochondria and uterine that makes the person different.
Cloning is not that far from procedures that are being done all the time, such as in vitro fertilization, where egg fertilization takes place in a lab and is then transferred to the uterus. In vitro fertilization usually requires the retrieval of many cells and can take several times to work if it does at all. It can also result in multiple pregnancies. Cloning is only another alternative to reproduction and unlike IVF; it takes very few cells and should work the first time with a single pregnancy making it a more efficient method of reproduction.
Some people argue against cloning because they think that it is a way of playing God. But in reality, doctors 'play God´ every day. It is commonly accepted that we create babies in test tubes and take birth control pills to prevent them, so why not clone them too? Today in the United States, many fetuses are screened for genetic or chromosomal abnormalities, with the option of abortion for those with defects. Is this not another way we 'play God´, making decisions on whether or not this fetus will live based on whether or not it has a defect? Why not go a step further and instead of eliminating the baby, make sure that there will be no defect to worry about.
In addition, because there are many benefits to cloning and since not everyone believes in a god why should religion be used in making decisions for people where religious morality is not even an issue? The beliefs of some people should not deprive others of the benefits of cloning. There are those with religious beliefs who think that taking antibiotics or receiving blood transfusions is wrong, but this does not stop the rest of the world from receiving the benefits from them. This is just another tool that can be used to our advantage, so why not do it if it can help improve the health of society? In the United States at least, there is supposed to be a separation of church and state, so anything having to do with God should play no part in law making. Religion and science are two very different things. Science is based on experimentation and observation, while religion is based on faith and things that cannot be proven. Making a law based on a religious, belief goes against our Constitution.
Furthermore, because a human clone is and should be thought of as a regular human, they are entitled to have the same basic rights as everyone else. There should not be the creation of entire embryos for the harvesting of parts because this goes against the rights of the clone and treats is as less than human. But, with new technology, scientists are finding ways to create entire separate organs and other tissues such as nerve or heart muscle cells without the creation of an entire person. These organs can be used for transplants and with scientists cloning organs from the own patient's DNA there should be no problem with immune rejection that can result with transplants from other sources. There is a large shortage in the number of organs available for transplants and continued research in cloning of this type could eliminate this problem.
Cloning could be used to reverse heart attacks by cloning healthy heart cells and injecting them into the damaged areas. This technology could also be used to produce skin for burn victims, brain cells, spinal cords, livers, lungs, and any other organs needed. But this may never come about if there are laws prohibiting cloning and its research.
Another benefit of cloning is that it can give couples that cannot reproduce a chance to have children who are biologically related to them, whereas they otherwise could not. This will also help those who are at a high risk for having a child with a genetic disease. They could clone one of themselves and have a healthy baby with their genes. This reproduction through cloning is close enough to other common reproduction and genetic-selection practices that it should not be treated any differently and given as an option.
This is also an issue of concern to the gay and lesbian community because cloning would allow them to reproduce themselves and many want this right. There are cloning rights groups who say that the government should not be allowed to control a person's reproductive rights and that your DNA is your own property and you should be allowed to do what you want with it.
An example of a situation where cloning could be lifesaving is in a situation where a child is terminally ill and in need of a bone marrow transplant. Many times in a case like this, the parents of the sick child will decide to have another child hoping that it will match with the sick child. If the child were cloned, then there would be a perfect match available.
Going a step further, with germ-line engineering, defective genes could be eliminated in children and in their offspring, virtually eliminating many inherited diseases. Some scientists believe that this could lead to the engineering of people completely resistant to other diseases, like AIDS and cancer, making society happier and healthier. This concept could also be used to make babies who are smarter and stronger. Several polls show that as many as 20% of parents see nothing wrong with genetically altering their children for health reasons and this number will probably increase as society becomes more informed and used to this new idea. This method is different from regular cloning that does not improve or change the genome, only duplicates it.
Those who say that cloning and genetic engineering do not value human life are wrong because as you can see these processes can make life longer and better for many in our society.
Animals are currently being cloned, like cattle and sheep that have been genetically engineered to maximize desirable traits. Research is also being done on the cloning of endangered species and dead animals. Many people do support cloning and whether the government makes laws against it or not, it will most likely take place. Then there are people like Dr. Richard Seed, a Harvard graduate who made headlines in 1997 when he claimed that he was going to attempt to create a human clone and had willing participants. It was also reported to the associated press in August of 1998, that a wealthy couple had given over 2 million dollars to Texas A&M University to have their dog cloned. This project is still in the workings though and it is not known if the doctors have actually began the process yet.
Conclusion:
In conclusion, whether the government bans cloning or not, it is inevitably going to take place. The discovery has been made and curious scientists are not just going to leave it alone. Decisions on whether or not your own DNA is replicated should be an issue that is private and left up to individuals, not the government. Since cloning is going to happen anyway, the government should accept it and regulate it to try to see that it is used to benefit the most people.
Bibliography:
Internet explorer:
www.google.co.uk
www.yahoo.co.uk
www.lycos.co.uk
Biology Advanced book 1
Biology Advanced book 2
