Cloning And Asexual Genetic Reproduction Biology Essay


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Cloning can be described as a form of asexual reproduction due to the obvious lack sexual interaction between two sexes. An organism such as a human or animal created through the process of cloning is a genetic duplicate of the existing organism from which it was essentially copied from. In 1997 Scottish scientists at the Roslin institute created the cloned sheep named Dolly. This was the first instance of a living mammal being successfully cloned from adult DNA.

Much controversy still revolves around the idea of cloning whether it is a single organ or a living organism. Some individuals question the morality of replicating a living organism. The debate continues between the benefits and the morality of this type of research. No matter what side of the debate, knowing the facts surrounding cloning is of great importance in understanding the processes and work involved. Only after reviewing the facts can one decide where to stand.

The first question that comes to mind is what is cloning and are there different types of cloning? There are three different types of cloning that exist today. These are recombinant DNA cloning, reproductive cloning and therapeutic cloning. Recombinant DNA cloning is a process that involves the transference of a particular DNA fragment from one organism to a self-replicating genetic element. This particular technology has been used since the 1970's and is quite commonly used today. In order to copy a chosen gene, a bacterial plasmid is used because they are "self-replicating extra-chromosomal circular DNA molecules." In order to truly clone a particular gene, DNA fragments that contain the gene of interest are isolated with restriction enzymes and then joined with the plasmid that was cut. Once this has happened, the recombinant DNA will be reproduced and thus creating a clone.

Reproductive cloning is used to produce any particular type of animal desired. An animal created from reproductive cloning has the exact same nuclear DNA as the original animal it was cloned from. This type of cloning was used to give life to Dolly, the first successfully cloned animal. The process of reproductive cloning begins by transferring genetic material from the nucleus of the original adult animal's cell into an egg that has had its genetic material removed. This egg serves as a blank in which scientists can then rebuild it with the donor DNA. The rebuilt egg then is treated with either chemicals or an electric current to begin the division of cells. This treatment is continued until the embryo reaches the correct stage. Once this stage has been reached, it is then placed into the uterus of a host female until the newly cloned animal is born. Unfortunately, this animal is not considered an identical clone. A portion of the clone's genetic material is derived from the mitochondria in the egg in which it developed. This gives way to certain mutations and shortens life spans and produces other defects.

Therapeutic cloning can be described as the creation of human embryos which are used for the purpose of research. The concept behind this is not to clone humans, but to produce stem cells for the treatment of diseases and to study the development of humans. The stem cells in embryos are extremely versatile because they can generate almost any specialized cell type in the body. In November of 2001, scientists from the Advanced Cell Technologies cloned the first human embryos. The process of cloning human embryos begins with removing genetic material from eggs harvested from women's ovaries. A skin cell is then added to the egg to create a new nucleus. After chemical stimulation the egg begins to divide. This process yields limited results at best. Out of a batch of eight eggs, only one was able to divide into 6 cells before it stopped completely.

With all the types of cloning in mind, this brings the question of how can these cloning technologies be used? There are various uses for cloning technology. Gene therapy could potentially treat genetic conditions. This can be done so by using virus vectors that carry the corrected copies of incorrectly functioning genes into the cells in order to correct problematic genes. Genes from different organisms can be introduced to another to improve the nutritional benefits, taste or its ability to protect itself from certain diseases.

If animals can be cloned with less failed attempts, reproductive cloning can be used to create animals with unique traits and qualities. Reproductive cloning can be used to increase populations of endangered animals or simply reproduce animals that are particularly difficult to breed naturally. Therapeutic cloning has by far the most potential. One day it can be used to create entire organs for transplant from a single cell. It can also be used to grow healthy cells to replace cells that were destroyed by degenerative diseases.

In 1952 the first animal was cloned, which was a tadpole. Since then what other animals have been cloned? Before Dolly, the sheep was cloned; scientists cloned animals from embryonic cells. Since those days scientists have been able to clone a variety of animals including sheep, goats, cows, mice, pigs, cats, rabbits, and a gaur. Today there are hundreds of clones in existence. The number of different species that can currently be cloned is quite limited. Research has shown that certain species could possibly be more resistant to somatic cell nuclear transfer than other species.

One of the most important questions at hand about cloning is what risks are involved with cloning? Only 10% of all cloning attempts create a successful offspring. It can take over 100 nuclear transfer procedures to produce one successful clone. The clones of particular animals tend to end up with weak immune systems which give way to infections, tumors, and several other complications. One large problem with clones is that they have a short life span and little data has been compiled because of this. In 2002, scientists at the Whitehead Institute for Biomedical Research determined that mice have compromised genomes. Over 10,000 liver and placenta cells were analyzed and it was determined that 4% of the genes are abnormal.

Knowing the risks of cloning brings into question should humans be cloned? Many scientists advise against human reproductive cloning. This is due to the very inefficient results of animal cloning thus far. Currently only one or two successful clones are produced out of over 100 experiments. Perhaps the greatest reason for not pursuing human cloning is the fact that little is known about reproductive cloning. Clones are also subject to many complications and early death which poses the question of whether it would be ethical. Another major factor is how mental development would be affected. This is a crucial part of human development and if that is compromised the results could be horrific.

Given all the benefits and drawbacks of cloning, it holds great potential to benefit human kind. Cloning could one day be used to treat a wide range of diseases and complications and improve the quality of life for people everywhere. Currently not enough is known about cloning to be used as a main stream treatment, but with more research it has the potential to positively impact humans.

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