Of The Clone's Genetic Materials example essay topic

Keller Hinson April 21, 2005 Biology 100 Jackson Cloning in Todays World Cloning 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 Technology The 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 Cloning Reproductive 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' (SENT), 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 clone's chromosomal or nuclear DNA is the same as the donor. Some of the clone's 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.

Dolly's 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 Cloning 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 Benefits Some scientists say that applying cloning procedures will further stem cell research. Stem cells can be grown to produce organs or tissues. The main benefit of being able to produce organs is to help those with particular organ failure. Many benefits to humans have come about as a result of cloning. Gene positional cloning is a major medical advancement, not only because of cloning, but because of the Human Genome Project as well. The goal of this procedure is to identify human disease genes and then clone them for further study.

This is done by studying several families who have the disorder. The gene for Huntington's Disease was found this way by examining a large Venezuelan family who had many members with the disease. Scientists, after isolating the gene, were able to test each member of the family to see if they had the disease. Another benefit from modern cloning is in agriculture.

Farmers and ranchers can now have their strongest crops and animals twinned so that they are less likely to contract diseases. Transplant patients may also soon benefit from cloning. Via cloning, British scientists have been able to insert portions of human DNA into several species including microbes, fish, rabbits, pigs, sheep, cows, and mice. Pig hearts are often used as transplants to replace diseased human hearts.

Donor pigs with human DNA could provide stronger hearts. Other reasons for cloning might include replacing lost or deceased family pets and repopulating endangered or even extinct species. Whatever the reasons, the new cloning technologies have sparked many ethical debates among scientists, politicians and the general public. Several governments have considered or enacted legislation to slow down, limit or ban cloning experiments outright. It is clear that cloning will be a part of our lives in the future, but the course of this technology has yet to be determined.