Cloning
Cloning is the process of creating an identical copy of an original organism or thing. A cloning in the biological sense, therefore, is a molecule, single cell (like bacteria, lymphocytes etc.) or multi-cellular organism that has been directly copied from and is therefore genetically identical to another living organism. Sometimes this term can refer to "natural" clones made either when an organism is asexually reproduced by chance (as with identical twins), but in common parlance, a clone is an identical copy created intentionally.
The term clone is derived from κλων, the Greek word for "twig". In horticulture, the spelling clon was used until the twentieth century; the final e came into use to indicate the vowel is a "long o" instead of a "short o". Since the term entered the popular lexicon in a more general context, the spelling clone has been used exclusively
The possibility of human cloning, raised when Scottish scientists at Roslin Institute created the much-celebrated sheep "Dolly" , aroused worldwide interest and concern because of its scientific and ethical implications. The feat, cited by Science magazine as the breakthrough of 1997, also generated uncertainty over the meaning of "cloning" --an umbrella term traditionally used by scientists to describe different processes for manuplicating biological material
History of Cloning
It seems that every week, newspapers report on new advances in the science of cloning. Everybody knows about Dolly the cloned sheep, but few people know all the details about cloning, including the fact that scientists have been working on it for over 100 years.
Cloning in Nature
Cloning has been going on in the natural world for thousands of years. A clone is simply one living thing made from another, leading to two organisms with the same set of genes. In that sense, identical twins are clones, because they have identical DNA. Sometimes, plants are self-pollinated, producing seeds and eventually more plants with the same genetic code. Some forests are made entirely of trees originating from one single plant; the original tree spread its roots, which later sprouted new trees. When earthworms are cut in half, they regenerate the missing parts of their bodies, leading to two worms with the same set of genes. However, the ability to intentionally create a clone in the animal kingdom by working on the cellular level is a very recent development.
Early Progress
The first cloned animals were created by Hans Dreisch in the late 1800's. Dreich's original goal was not to create identical animals, but to prove that genetic material is not lost during cell division. Dreich's experiments involved sea urchins, which he picked because they have large embryo cells, and grow independently of their mothers. Dreich took a 2 celled embryo of a sea urchin and shook it in a beaker full of sea water until the two cells separated. Each grew independently, and formed a separate, whole sea urchin.
In 1902, another scientist, embryologist Hans Spemman, used a hair from his infant son as a knife to separate a 2-celled embryo of a salamander, which also grow externally. He later separated a single cell from a 16-celled embryo. In these experiments, both the large and the small embryos developed into identical adult salamanders. Spemman went on to propose what he called a "fantastical experiment" -- to remove the genetic material from an adult cell, and use it to grow another adult. In this way, he theorized, he would be able to prove that no genetic material was lost as cells grew and divided.
New Advances
There were no major advances in cloning until November of 1951, when a team of scientists in Philadelphia working at the lab of Robert Briggs cloned a frog embryo. This team did not simply break off a cell from an embryo, however. They took the nucleus out of a frog embryo cell and used it to replace the nucleus of an unfertilized frog egg cell, completing the "fantastical experiment" of nearly 50 years before. Once the egg cell detected that it had a full set of chromosomes, it began to divide and grow. This was the first time that this process, called nuclear transplant, was ever used, and it continues to be used today, although the method has changed slightly.
 In 1962, biologist John Gurdon of Oxford University announced that he had used the nucleus of fully differentiated adult intestinal cells to clone South African frogs. Gurdon's results electrified the scientific community, but some scientists remained skeptical and began to find flaws in his work.
 In 1963, the British biologist J.B.S. Haldane is credited to have coined the term "clone" in a speech entitled "Biological Possibilities for the Human Species of the Next Ten-Thousand Years." Even though many scientists had described, and even completed the cloning process by this time, the term "cloning" had never been used to describe such experiments.
 In 1966, Marshall Niremberg, Heinrich Mathaei, and Severo Ochoa crack the genetic code. The cracking of the genetic code opened the door for the explosion of genetic engineering studies and achievements beginning in the late 1970's.
 In 1967, the enzyme DNA ligase was isolated. DNA ligase binds together strands of DNA. Its discovery, with the isolation of the first restriction enzyme 1970, paved the way for the first recombinant DNA molecules to be created by Paul Berg in 1972. In the recombinant DNA process, ligase bonds the "sticky" ends of complimentary DNA strands previously cut by a restriction enzyme.
 In 1969, James Shapiero of Harvard University, working with Johnathan Beckwith announce that they had isolated the first gene. The gene directed the digestion of sugar in a certain type of bacteria. Shapiero and Beckwith's discovery part of a wave of molecular biology discoveries directly following the 1966 cracking of the genetic code. The announcement also increased the public's concern about the growing power of molecular biologists.
 In 1970, both Howard Temin and David Baltimore, working independently, isolated the first restriction enzyme. The restriction enzyme, called Reverse Transcriptase, cut DNA molecules at precise locations. This capability led to the future manipulation of DNA.
 In 1972, Paul Berg of Stanford University created the first recombinant DNA molecules by combining the DNA of two different organisms.
 In 1973, Stanley Cohen and Herbert Boyer created the first recombinant DNA organism using recombinant DNA techniques pioneered a year earlier by Paul Berg. Recombinant DNA, also called gene splicing, is a technique that allows scientists to manipulate the DNA of an organism.
 In 1977, a German scientist shocked the world, claiming to have cloned three mice from embryos. Although embryos had been cloned before, no one had been able to do the experiment with mice because the cells were so small and the tools so large that the cells were traumatized and would eventually die after a few divisions. He instantly became famous, telling the world how he cloned his mice. However, he refused to actually demonstrate any of his techniques, and when other scientists couldn't replicate his work, he came under suspicion. He was challenged -- repeat his work or be discredited. He accepted.
He claimed to work nights and mornings when no one was around, but the equipment was never disturbed. He showed off his mouse embryos' growth daily, even though a malfunction in the water purification system left other scientists at his lab unable to grow other embryos. Later, in his cabinet, test tubes were found with mouse embryos in them, each at a different stage of development. Most scientists do not believe that this scientist was ever able to clone adult mice.

 In 1978, a science fiction writer published a book claiming that a millionaire (known to the readers only as Max) had come to him because of his connections as a writer, and asked the him to arrange for Max to be cloned. The author eventually agreed, as the story goes, and Max was cloned. The book was ranked in the Top 10 list of popular books. Scientists who read his book, however, noticed discrepancies between the book and scientific data. One man who was quoted in the book was angry enough to sue. The publisher admitted that the book was a hoax, but the author maintains his claim to this day.
Within these two years, two front-page advances in cloning were discovered to be, most likely, frauds. As a direct result, many scientists began to claim that cloning of mammals was impossible. Funding and interest dropped, and cloning returned to the realm of science fiction for several years.
 In 1979, One of the most surprising of modern genetics announcements was made, Karl Illmensee claimed to have cloned three mice The announcement came at a time where a succession of failed cloning attempts were beginning to convince biologists that the cloning of a mammal was impossible.
 In 1983, In what has been called by some the greatest achievement of modern molecular biology, Kary B. Mullis developed the polymerase chain reaction (PCR) in 1983. PCR allows the rapid synthesis of designated fragments of DNA. Using the technique, over one billion copies can be synthesized in a matter of hours.
 In 1983 Davor Solter, working with David McGrath, attempted to clone mice using his own version of the nuclear transfer method. They wanted to use the cloning experiment to determine if DNA specializes as a cell specializes.
 In 1984, Danish scientist Steen Willadsen succeeded in cloning a sheep from embryo cells. His work was the first verified cloning of a mammal using the method of nuclear transfer.
 In 1985 Steen Willadsen, the first to clone a farm animal using the nuclear transfer method, joined Grenada Genetics, a bioengineering company. Willadsen used his cloning technique to duplicate the embryos of prize cattle. Grenada Genetics saw the profitability of the future cattle cloning industry. Top breed cattle embryos were highly desired by farmers, Willadsen's procedure mass produced identical copies of such embryos.
 In 1986, while working at Grenada Genetics, Steen Willadsen cloned a cow using differentiated, one week old embryo cells. The work proved that the genetic information of a cell did not diminish as a cell specialized and that DNA could return to its original state. Willadsen never officially published his results, but the work was a strong influence in Ian Wilmut's decision to attempt to clone from adult cells, which he accomplished in the famous 1996 birth of "Dolly.”
 In October of 1990, the National Institutes of Health officially began the Human Genome Project, a massive international collaborative effort to locate the 50,000 to 100,000 genes and sequence the estimated 3 billion nucleotides making up the entire human genome. By determining the complete genetic sequence, scientists hope to begin correlating human traits with certain genes. With this information, medical researchers have begun to determine the intricacies of human gene function, including the source of genetic disorders and diseases that have plagued medical researchers for years.
 In July 1995, Ian Wilmut and Keith Campbell of the Roslin Institute in Scotland successfully cloned two sheep, named Megan and Morag, from differentiated embryo cells. The idea to clone sheep was arrived at by Ian Wilmut as an answer to a gene insertion project he was researching. At the time, time inserting genes into embryo cells was a difficult and tedious process. Few embryos survived the insertion of a gene, even fewer incorporated the gene into their genetic code, and even fewer organisms developed properly and used the gene in all of their cells.
 On July 5, 1996, Dolly, the first organism ever to be cloned from adult cells, was born. Ian Wilmut and Keith Campbell, researchers at the Roslin Institute in Scotland created Dolly using a technique similar to that with which they created the first sheep from differentiated embryo cells in 1995.
 On March 4, 1997, President Clinton, in response to the large scale human cloning ethics debate brought about by Ian Wilmut's announcement of the creation of Dolly, proposed a five year moratorium on federal and privately funded human cloning research. In addition to this proposal, Clinton asked the National Bioethics Advisory Commission to review the prospects of human cloning and determine if legal preventive actions should be taken.
 On December 5, 1997, Harvard graduate Richard Seed announced that he planned to clone a human being before any federal laws could be enacted to ban the process. Seed's announcement added fuel to the raging ethical debate on human cloning that had been sparked by Ian Wilmut's creation of Dolly, the first clone obtained from adult cells.
 In July 1997, building upon their success of the creation of Dolly, the first animal cloned from adult cells, Ian Wilmut and Keith Campbell created Polly, a Poll Dorset lamb cloned from skin cells grown in a lab and genetically altered to contain a human gene. Polly's birth signified the first step in the application of cloning technology to the production of a useful product. Most scientists believe that most beneficial application of cloning will come from the exact reproduction of animals genetically altered to produce human proteins or organs more easily accepted in transplants. Wilmut and Campbell's creation of Polly surprised the scientific community by how fast cloning technology was progressing. The cloning of genetically altered farm animals was not expected for another five years.
In July 1998, Ryuzo Yanagimachi, Toni Perry, and Teruhiko Wakayama of the University of Hawaii announced that they had cloned fifty mice from adult cells since October of 1997. The new cloning technique, which has proven to be more efficient than that performed by Ian Wilmut in his cloning of Dolly, was developed by postdoctoral student Wakayama in his spare time.

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Dolly the Sheep

Dolly (July 5, 1996 – February 14, 2003), a ewe, was the first mammal to have been successfully cloned from an adult somatic cell. She was cloned at the Roslin Institute in Midlothian, Scotland, and lived there until her death when she was six years old. Her birth was announced on February 22, 1997.
The sheep was originally code-named "6LL3". The name "Dolly" came from a suggestion by the stockmen who helped with her birth, in honor of Dolly Parton, because it was a mammary cell that was cloned[1]. The technique that was made famous by her birth is somatic cell nuclear transfer, in which a cell is placed in a de-nucleated ovum, the two cells fuse and then develop into an embryo. When Dolly was cloned in 1996 from a cell taken from a six-year-old ewe, she became the center of much controversy that still exists today.


On April 9, 2003 her stuffed remains were placed at Edinburgh's Royal Museum, part of the National Museums of Scotland.
Dolly was created by a research team managed by Ian Wilmut at the Roslin Institute in Scotland. The goal of the research was the reliable reproduction of mammals genetically modified to produce therapeutic proteins in their milk. Wilmut's team had already created 2 sheep clones from embryonic cells grown in culture called Megan and Morag; the work was published in Nature in 1996 Dolly was a Finn Dorset lamb, created from fully differentiated adult mammary cells using a technique called somatic cell nuclear transfer; her creation was described in a Nature publication in 1997. Dolly was the first mammalian clone produced from an adult somatic cell.
Premature aging
In 1999 research was published in the journal Nature suggesting that Dolly may have been susceptible to premature aging, due to shortened telomeres in her cells. It was speculated that these were passed on from her donor sibling, who was six years old when the genetic material was taken from her, so that Dolly may have been genetically six years old at birth. This is because telomere length is reduced after each cell division, which requires DNA replication before mitosis occurs. The polymerase, part of the replication machinery, cannot reach the end of the chromosome being replicated and clips a little of the telomere at the end off every time replication occurs.
Possible signs of her condition were reported in January 2002, when Dolly was five years old. She had developed a potentially debilitating form of arthritis at an unusually early age. This supported the theory of premature senescence, although Dr. Dai Grove-White of the Faculty of Veterinary Science at Liverpool University was reported as saying, "Conceivably arthritis could be due to the cloning but equally it could not be. For all we know, she may have damaged her leg jumping over a gate and developed arthritis."
Others speculate that Dolly's arthritis resulted from her lifestyle as a scientific curiosity and protected specimen due to a lack of normal outdoor exercise and unnatural stress on her joints.
The arthritis further fueled worry among some that this form of cloning may not be appropriate for mammals, and there is now a consensus both in- and outside scientific community that at this point the risk of unforeseen effects of cloning on the clone makes experiments in human reproductive cloning premature and unethical.
Supporters of this method of cloning counter that the technique used to clone Dolly simply needs to be refined. However, others contend that with very limited understanding of the nascent field of applied genetics, scientists can not and should not attempt to control the action of so many genes at once. Many outside the scientific community have stated that this is vindication for their initial assertions that any form of cloning is ethically wrong and should be banned.

Death
On February 15, 2003 it was announced that Dolly had died from a progressive lung disease. A necropsy confirmed she had Ovine Pulmonary Adenocarcinoma (Jaagsiekte), a fairly common disease of sheep caused by a retrovirus. Roslin scientists stated that they did not think there was a connection with Dolly being a clone, and that other sheep on the farm had similar ailments. Such lung diseases are especially a danger for sheep kept indoors, as Dolly had to be for security reasons.

Legacy

After the cloning was successfully demonstrated by Dolly's creators , many other large mammals have been cloned, including horses and bulls. Cloning is now considered a promising tool for preserving endangered species, usually by those who do not work in species conservation. Most animal conservation professionals point out that cloning does not alleviate the problems of loss of genetic diversity (see inbreeding) and habitat, ergo must be considered an experimental technology for the time being, and all in all would only rarely be worth the cost, which on a per-individual basis far exceeds conventional techniques such as captive breeding or embryo transfer. The 2000-2001 attempt to clone a gaur failed, with the animal, "Noah", dying 2 days after birth, and the attempt to clone argali sheep did not produce viable embryos. The attempt to clone a banteng bull was more successful, as were the attempts to clone mouflon, both resulting in viable offspring. The banteng example is a case illustrating the circumstances under which the uncertainties of cloning attempts are outweighed by the benefit

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Cloning Ethics

Is Cloning Wrong or Right?
Can we and should we clone humans?

Wrong

The biggest problem with the use of cloning on a large is scale is the decline in genetic diversity. Think about it, if everyone has the same genetic material, what happens if we lose the ability to clone. We would have to resort to natural reproduction, causing us to inbreed, which will cause many problems. Also, if a population of organisms has the same genetic information, then the disease would wipe out the entire population. Helping endangered species by cloning will not help the problem. Currently, zoologists and environmentalists trying to save endangered species are not so much having trouble keeping population numbers up, but not having any animals to breed that are not cousins. The technique of nuclear transfer is also early in its developmental stages. Thus, errors are occurring when scientists carry out the procedure. For instance, it took 277 tries to produce Dolly, and Roslin scientists produced many lambs with abnormalities. If we tried to clone endangered species we could possibly kill the last females integral to the survival of a species. This may be the main reason science is holding out on cloning humans.

Right

The goals and purposes for cloning range from making copies of those that have deceased to better engineering the offspring in humans and animals. Cloning could also directly offer a means of curing diseases or a technique that could extend means to acquiring new data for the sciences of embryology and how organisms develop as a whole over time. Currently, the agricultural industry demands nuclear transfer to produce better livestock. Cloning could massively improve the agricultural industry as the technique of nuclear transfer improves. Currently, change in the phenotype of livestock is accomplished by bombarding embryos of livestock with genes that produce livestock with preferred traits. However, this technique is not efficient as only 5 percent of the offspring express the traits. Scientists can easily genetically alter adult cells. Thus, cloning from an adult cell would make it easier to alter the genetic material. The goal of transgenic livestock is to produce livestock with ideal characteristics for the agricultural industry and to be able to manufacture biological products such as proteins for humans. Farmers are attempting to produce transgenic livestock already, but not efficiently, due to the minimal ability to alter embryos genetically, as stated above. Researchers can harvest and grow adult cells in large amounts compared to embryos. Scientists can then genetically alter these cells and find which ones did transform and then clone only those cells.

Can we and should we clone humans?

Cloning humans has recently become a possibility that seems much more feasible in today's society than it was twenty years ago. It is a method that involves the production of a group of identical cells or organisms that all derive from a single individual. It is not known when or how cloning humans really became a possibility, but it is known that there are two possible ways that we can clone humans. The first way involves splitting an embryo into several halves and creating many new individuals from that embryo. The second method of cloning a human involves taking cells from an already existing human being and cloning them, in turn creating other individuals that are identical to that particular person. With these two methods almost at our fingertips, we must ask ourselves two very important questions: Can we do this, and should we? There is no doubt that many problems involving the technological and ethical sides of this issue will arise and will be virtually impossible to avoid, but the overall idea of cloning humans is one that we should accept as a possible reality for the future.
Embryonic cloning could be a valuable tool for the studying of human development, genetically modifying embryos, and investigating new transplant technologies. Using cloning to produce offspring for the sake of their organs is an issue that we must also face and question whether or not it is morally right. No one will say that it is okay to kill a human being for the sake of their organs, but many have no objection to cloning thousands of individuals that look alike. Technology seems to take away many of the morals that we have worked so hard to install in society. Most people only seem to want to cater to their own needs and do not bother to consider the consequences that society and the clone may have to face.
How can cloning technologies be used?
Recombinant DNA technology is important for learning about other related technologies, such as gene therapy, genetic engineering of organisms, and sequencing genomes. Gene therapy can be used to treat certain genetic conditions by introducing virus vectors that carry corrected copies of faulty genes into the cells of a host organism. Genes from different organisms that improve taste and nutritional value or provide resistance to particular types of disease can be used to genetically engineer food crops. With genome sequencing, fragments of chromosomal DNA must be inserted into different cloning vectors to generate fragments of an appropriate size for sequencing.
If the low success rates can be improved (Dolly was only one success out of 276 tries), reproductive cloning can be used to develop efficient ways to reliably reproduce animals with special qualities. For example, drug-producing animals or animals that have been genetically altered to serve as models for studying human disease could be mass-produced.
Reproductive cloning also could be used to repopulate endangered animals or animals that are difficult to breed. In 2001, the first clone of an endangered wild animal was born, a wild ox called a gaur. The young gaur died from an infection about 48 hours after its birth. In 2001, scientists in Italy reported the successful cloning of a healthy baby mouflon, an endangered wild sheep. The cloned mouflon is living at a wildlife center in Sardinia. Other endangered species that are potential candidates for cloning include the African bongo antelope, the Sumatran tiger, and the giant panda. Cloning extinct animals presents a much greater challenge to scientists because the egg and the surrogate needed to create the cloned embryo would be of a species different from the clone.
Therapeutic cloning technology may some day be used in humans to produce whole organs from single cells or to produce healthy cells that can replace damaged cells in degenerative diseases such as Alzheimer's or Parkinson's. Much work still needs to be done before therapeutic cloning can become a realistic option for the treatment of disorders.
Can organs be cloned for use in transplants?
Scientists hope that one day therapeutic cloning can be used to generate tissues and organs for transplants. To do this, DNA would be extracted from the person in need of a transplant and inserted into an enucleated egg. After the egg containing the patient's DNA starts to divide, embryonic stem cells that can be transformed into any type of tissue would be harvested. The stem cells would be used to generate an organ or tissue that is a genetic match to the recipient. In theory, the cloned organ could then be transplanted into the patient without the risk of tissue rejection. If organs could be generated from cloned human embryos, the need for organ donation could be significantly reduced.
Many challenges must be overcome before "cloned organ" transplants become reality. More effective technologies for creating human embryos, harvesting stem cells, and producing organs from stem cells would have to be developed. In 2001, scientists with the biotechnology company Advanced Cell Technology (ACT) reported that they had cloned the first human embryos; however, the only embryo to survive the cloning process stopped developing after dividing into six cells. In February 2002, scientists with the same biotech company reported that they had successfully transplanted kidney-like organs into cows. The team of researchers created a cloned cow embryo by removing the DNA from an egg cell and then injecting the DNA from the skin cell of the donor cow's ear. Since little is known about manipulating embryonic stem cells from cows, the scientists let the cloned embryos develop into fetuses. The scientists then harvested fetal tissue from the clones and transplanted it into the donor cow. In the three months of observation following the transplant, no sign of immune rejection was observed in the transplant recipient.
Another potential application of cloning to organ transplants is the creation of genetically modified pigs from which organs suitable for human transplants could be harvested . The transplant of organs and tissues from animals to humans is called xenotransplantation.
Why pigs? Primates would be a closer match genetically to humans, but they are more difficult to clone and have a much lower rate of reproduction. Of the animal species that have been cloned successfully, pig tissues and organs are more similar to those of humans. To create a "knock-out" pig, scientists must inactivate the genes that cause the human immune system to reject an implanted pig organ. The genes are knocked out in individual cells, which are then used to create clones from which organs can be harvested. In 2002, a British biotechnology company reported that it was the first to produce "double knock-out" pigs that have been genetically engineered to lack both copies of a gene involved in transplant rejection. More research is needed to study the transplantation of organs from "knock-out" pigs to other animals.
The Potential Advantages and Disadvantages of Cloning:

Advantages:
With this controversial issue, the possibilities of advantages and disadvantages must be discussed. There are several advantages to the cloning of animals and to the cloning of human cells. Along with each of the advantages, however, there are disadvantages, risks, and warnings.
There are five important reasons why animal cloning might be useful: (1) to generate groups of genetically identical animals for research purposes; (2) to rapidly propagate desirable animal stocks; (3) to improve the efficiency of generating and propagating transgenic livestock; (4) to produce targeted genetic alterations in domestic animals; (5) to pursue basic knowledge about cell differentiation.
Cloning animals for research purposes is attractive to many scientists, because the experimental variation that often occurs with genetic differences is eliminated. This process is limited in its usefulness, however, because keeping a homozygous line is going to be difficult. Also, the overall process promises to be expensive for most animals.
Having a speedy method to breed favorable livestock has great commercial importance. Nuclear transfer may be the wave of the future to rapidly produce desirable stocks of animals. The ultimate consequences could be dangerous, however, because genetic diversity could be eliminated. Strict regulation of cloning would ensure that this would not happen, though.
The improved generation and propagation of transgenic livestock becomes of interest to the pharmaceutical and medical world. Genetically altering farm animals by the introduction and expression of genes from other species proves to be a useful technology for the future. For example, the milk of livestock animals can be modified to contain large amounts of pharmaceutically important proteins such as insulin or factor VIII for treatment of human disease by expressing human genes in the mammary gland. Also, transgenic animals could become useful for organ transplantation into humans.
Generating targeted gene alterations in domestic animals can be helpful in studying mutations of genes in a very controlled manner. Gene targeting approaches can also be used to ensure correct tissue-specific expression of foreign genes and to suppress the expression of genes in inappropriate tissues. It could also be used to directly alter normal genes, which could influence animal health and productivity.
Basic research on cell differentiation has come about with the arrival of Dolly. Developmental biologists will want to know which genes are reprogrammed, when they are expressed, and in what order. This may or may not shed some light on the specialization that occurs during the development of therapies to treat human disease.
The agricultural industry could reek the benefits of this new technology by having the ability to produce multiple identical copies of a cow that produces a lot of mile, a sheep that produces a lot of wool, and so on. They could create an elite stock of farm animals.
The most exciting prospect here is to modify a sheep CTFR gene to create a model of cystic fibrosis (CF) for gene therapy. In a classy move, Ian Wilmut sold the first wool shorn from Dolly to raise money for the care and treatment of kids with CF.
There are five potential uses for cloning humans or human cells: (1) a research tool to understand how genes in cells can be switched off and on; (2) growing new skin for burn victims; (3) culturing bone marrow that could be used to treat cancer patients; (4) manipulating genes to cure sickle cell anemia; (5) potential application in treating infertility.
A more controversial benefit is to provide children for lesbian couples. Normally they need an outsider to donate sperm; with cloning they would be able to avoid this.
Disadvantages:

There are several disadvantages associated with cloning, such as significant scientific uncertainty, medical risks, potential effects of aging, somatic mutation, and improper imprinting. A cloned child is not really a couple’s genetic child, but the child of only one of them. That imbalance may produce strains on the marriage the child might suffer identity confusion, and there is a risk of perpetuating the cause of sterility.Reproductive cloning is expensive and highly inefficient. More than 90% of cloning attempts fail to produce viable offspring. More than 100 nuclear transfer procedures could be required to produce one viable clone. In addition to low success rates, cloned animals tend to have more compromised immune function and higher rates of infection, tumor growth, and other disorders. Japanese studies have shown that cloned mice live in poor health and die early. About a third of the cloned calves born alive have died young, and many of them were abnormally large. Many cloned animals have not lived long enough to generate good data about how clones age. Appearing healthy at a young age unfortunately is not a good indicator of long term survival. Clones have been known to die mysteriously. For example, Australia's first cloned sheep appeared healthy and energetic on the day she died, and the results from her autopsy failed to determine a cause of death.
In 2002, researchers at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, reported that the genomes of cloned mice are compromised. In analyzing more than 10,000 liver and placenta cells of cloned mice, they discovered that about 4% of genes function abnormally. The abnormalities do not arise from mutations in the genes but from changes in the normal activation or expression of certain genes.
Problems also may result from programming errors in the genetic material from a donor cell. When an embryo is created from the union of a sperm and an egg, the embryo receives copies of most genes from both parents. A process called "imprinting" chemically marks the DNA from the mother and father so that only one copy of a gene (either the maternal or paternal gene) is turned on. Defects in the genetic imprint of DNA from a single donor cell may lead to some of the developmental abnormalities of cloned embryos.

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I believe in God even though He is silent.

Something amazing about cloning


Mary Had A Little Lamb
Mary had a little lamb, its fleece was slightly gray
It didn’t have a father, just some borrowed DNA.
It sort of had a mother, though the ovum was on loan,
It was not so much a lambkin as a little lamby clone.
And soon it had a fellow clone, and soon it had some more,
They followed her to school one day, all cramming through the door.
It made the children laugh and sing, the teachers found it droll,
There were too many lamby clones, for Mary to control.
No other could control the sheep, since the programs didn’t vary,
So the scientists resolved it all, by simply cloning Mary.
But now they feel quite sheepish, those scientists unwary,
One problem solved but what to do, with Mary, Mary, Mary.

__________________
I believe in God even though He is silent.