Cloning in Todays WorldJoin now to read essay Cloning in Todays WorldKeller HinsonApril 21, 2005Biology 100JacksonCloning in Todays WorldCloning is the creation of an organism that is an exact genetic copy of another. This means that every single bit of DNA is the same between the two. There are different types of cloning however, and cloning technologies can be used for other purposes besides producing the genetic twin of another organism. The following types of cloning technologies will be discussed: (1) recombinant DNA technology or DNA cloning, and (2) reproductive cloning.
Recombinant DNA TechnologyThe term recombinant DNA technology refers to the transfer of DNA from one organism to a self replicating genetic element such as a bacterial plasmid. The DNA of interest can then be propagated in a foreign host cell. Plasmids are self-replicating extra-chromosomal circular DNA molecules and are used to copy genes and other pieces of chromosomes to generate enough identical material for further study. To clone a gene, a DNA fragment containing the gene is isolated using restriction enzymes and then united with a plasmid that has been cut with the same restriction enzyme. Following introduction into suitable host cells, the recombinant DNA can then be reproduced along with the host cell. This technology has been around since the 1970’s, and it has become a common practice in molecular biology labs today.
Reproductive CloningReproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. An example of reproductive cloning occurred in 1996 when researchers at the Roslin Institute in Scotland managed to create a lamb named Dolly. In a process called “somatic cell nuclear transfer” (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed. The reconstructed egg containing the DNA from a donor cell must be treated with chemicals or electric current in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth. Dolly or any other animal created using nuclear transfer technology is not truly an identical clone of the donor animal. Only the clones chromosomal or nuclear DNA is the same as the donor. Some of the clones genetic materials come from the mitochondria in the cytoplasm of the enucleated egg. Mitochondria, which are organelles that serve as power sources to the cell, contain their own short segments of DNA. Acquired mutations in mitochondrial DNA are believed to play an important role in the aging process. Dollys success is truly remarkable because it proved that the genetic material from a specialized adult cell, such as an udder cell programmed to express only those genes needed by udder cells, could be reprogrammed to generate an entire new organism.
These cloning technologies are being used in a number of ways. However these technologies have met strong opposition. While some feel cloning a benefit to science and society, others are against its procedures. There are arguments that advocate the usage of cloning and arguments that advocate the opposite. Here will discuss the benefits and risks these delicate technologies pose.
Risks of CloningReproductive 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, Australias first cloned sheep appeared
Practical Cloning Methods “Cloning is a way to make a human clone, but in the actual case of cloning it differs from what one would think if the cloning was a physical process. The cloning process is based on the concept that the DNA is just as much a piece of DNA as the tissues are, if not less so. As a result, there are two components that have changed: one component of tissue DNA, the other is less complex, and can be used to make a human clone.” -A. J. Bader, University of Arizona.
Cloning from a human egg cells “A human egg and its DNA is called a cloned human brain cell. It has the same cells as the placenta of a human egg and it can survive for more than 2 hours a day for up to two months. The cells can be transferred from one egg to another if the two cells become too difficult to replicate, or if the new cell is too small to carry. The embryos can be produced in several different ways. A single egg is sent to the laboratory, containing several placenta units that are grown into human embryos. The placenta can take up to 10 days to grow.” -Cloning from a human egg cells “Scientists in the U.S., Italy, Canada and Germany have created two types of human egg cells. Each has a unique set of cells called a progenitor. The cells contain a single nucleus that grows into the egg itself, usually the heart cell, and which is called the embryonic stem cell. In both studies, both cells received embryonic stem cells as donor cells and the same stem cells are injected into the human egg. The end result is the progenitor in an egg with less than 10% success rate.” -Cloning from a human egg cells “There are also two types of human eggs, one made of normal tissues and one of an organized embryo. Both of these human egg cells are different from the regular donor. Both can be created by using genetic engineering. There is nothing more complicated than this. If the transplant is successful in human cells, the egg will have a normal cell type, and all progenitors will become normal. It is not a matter if the whole cell dies, it is the fact that it will have been transplanted.” -Cloning from a human egg cells “In all cultures of human cells, the stem cells have been transferred from one egg to another from one place to another of their intended home. Thus a human egg cell is essentially indistinguishable from an adult cell. Therefore, the transplanted human cell can be considered a human egg.” -Cloning from a human egg cells “Researchers from California, France, and Singapore have developed an “eccentric cloning” technique based on cloning eggs. The purpose of this technique is to transplant two or three embryos which are part of the same litter, but in different sites which are also known as “placenta layers.” The eggs can be transferred from one egg to another and remain healthy even as both groups of eggs grow back. The transfer process allows the transfer of eggs in two or three areas at once, for the sake of a relatively small growth of the eggs which may not occur in the future.” -Cloning from human egg cells “Some people have reported seeing a long-lasting difference in their normal blood flow with using a human egg