The possibility of human cloning was raised when Scottish scientists at Roslin Institute created the much-celebrated sheep "Dolly" (Lauritzen 57-64). Dolly aroused worldwide interest and concern because of the scientific and ethical implications in creating her. 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 duplicating biological material. (Murray, 41) When the media report on cloning in the news, they are usually talking about only one type called reproductive cloning. There are different types of cloning however, and cloning technologies can be used for other purposes besides producing the genetic twin of another organism. A basic understanding of the different types of cloning is key to taking an informed stance on current public policy issues and making the best possible personal decisions. (Murray, 41)
The following three types of cloning technologies are the most progressive: (1) recombinant DNA technology or DNA cloning, (2) reproductive cloning, and (3) therapeutic cloning. ...
Scientists studying a particular gene often use bacterial plasmids to generate multiple copies of the same gene. Plasmids are self-replicating extra-chromosomal circular DNA molecules, distinct from the normal bacterial genome (see image to the right). Plasmids and other types of cloning vectors are used by Human Genome Project researchers to copy genes and other pieces of chromosomes to generate enough identical material for further study. (Walters, 69)
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. (Lauritzen 57-64) 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. (Walters 69)
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