About Cloning

Cloning is the process of creating genetically identical copies of living things. Cloning uses copies of DNA fragments and cells. The Greek word "clone" means "twig." This meaning is referring to the process at which a new plant can be grown from a twig. There are three types of cloning: DNA cloning, reproductive cloning and therapeutic cloning.

DNA Cloning

DNA cloning is when a fragment of DNA is transferred from a living thing by the use of restriction enzymes into a genetic element such as bacterial plasmid. To clone the DNA, the fragment is united with a plasmid that was cut with identical enzymes. This technology began in the 1970s and is now a common practice in biology labs.

Reproductive Cloning

Reproductive cloning is when genetic material is transferred from a donor adult egg nucleus to a new reconstructed egg. The new egg contains the DNA from the donor cells and is treated with chemicals and electric currents that stimulate cell division. When the cloned embryo starts growing normally, it is then transferred into a female host's uterus where it grows and is then born.

Therapeutic Cloning

Therapeutic cloning is when a human embryo is used in research to harvest stem cells. Stem cells can then be used to study human body development and to treat diseases. After an egg has been divided for five days, the embryo is removed and destroyed. This process raises a number of ethical concerns. Researchers believe that through stem cell research, these stem cells can be used to treat patients with various diseases such as heart disease and cancer.

Cloned Animals

The first animal, a tadpole, was cloned in 1952. In 1996, the first mammal was created with the use of a cell from another adult animal. This mammal was a sheep named "Dolly." Since then scientists have been cloning other animals including cows, goats, mice, pigs, and rabbits. Many cloned animals are still alive today but are limited to a small number of species. Different species cloning attempts have been made but were not successful.

Human Cloning

Many physicians and scientists have made public statements advising against the cloning of human beings due to a lack of understanding about reproductive cloning. Intellect and mood are not important for the development of an animal, but for a human being these factors are crucial. Today, there are too many unknown factors in reproductive cloning to attempt cloning humans, and the process could be dangerous.

Resources

• National Human Genome Research Institute