Cloning is the process of making a genetically identical organism through nonsexual means. It has been used for many years to produce plants (even growing a plant from a cutting is a type of cloning). Animal cloning has been the subject of scientific experiments for years, but garnered little attention until the birth of the first cloned mammal in 1997, a sheep named Dolly.
Nature has been cloning organisms for billions of years. For example, when a strawberry plant sends out a runner (a form of modified stem), a new plant grows where the runner takes root. That new plant is a clone. Similar cloning occurs in grass, potatoes and onions.
People have been cloning plants in one way or another for thousands of years. For example, when you take a leaf cutting from a plant and grow it into a new plant (vegetative propagation), you are cloning the original plant because the new plant has the same genetic makeup as the donor plant. Vegetative propagation works because the end of the cutting forms a mass of non-specialized cells called a callus. With luck, the callus will grow, divide and form various specialized cells (roots, stems), eventually forming a new plant.
More recently, scientists have been able to clone plants by taking pieces of specialized roots, breaking them up into root cells and growing the root cells in a nutrient-rich culture. In culture, the specialized cells become unspecialized (dedifferentiated) into calluses. The calluses can then be stimulated with the appropriate plant hormones to grow into new plants that are identical to the original plant from which the root pieces were taken.
This procedure, called tissue culture propagation, has been widely used by horticulturists to grow prized orchids and other rare flowers.
Plants are not the only organisms that can be cloned naturally. The unfertilized eggs of some animals (small invertebrates, worms, some species of fish, lizards and frogs) can develop into full-grown adults under certain environmental conditions -- usually a chemical stimulus of some kind. This process is called parthenogenesis, and the offspring are clones of the females that laid the eggs.
Another example of natural cloning is identical twins. Although they are genetically different from their parents, identical twins are naturally occurring clones of each other.
Scientists have experimented with animal cloning, but have never been able to stimulate a specialized (differentiated) cell to produce a new organism directly. Instead, they rely on transplanting the genetic information from a specialized cell into an unfertilized egg cell whose genetic information has been destroyed or physically removed.
In the 1970s, a scientist named John Gurdon successfully cloned tadpoles. He transplanted the nucleus from a specialized cell of one frog (B) into an unfertilized egg of another frog (A) in which the nucleus had been destroyed by ultraviolet light. The egg with the transplanted nucleus developed into a tadpole that was genetically identical to frog B.
While Gurdon's tadpoles did not survive to grow into adult frogs, his experiment showed that the process of specialization in animal cells was reversible, and his technique of nuclear transfer paved the way for later cloning successes.
The main reason to clone plants or animals is to mass produce organisms with desired qualities, such as a prize-winning orchid or a genetically engineered animal -- for instance, sheep have been engineered to produce human insulin. If you had to rely on sexual reproduction (breeding) alone to mass produce these animals, then you would run the risk of breeding out the desired traits because sexual reproduction reshuffles the genetic deck of cards.
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.
Who is it for ?
Therapeutic cloning can be used to fight deseases and create
organs artificially. Once specialized cells can be derived from cloned embryos
the following diseases threatening millions of people on earth can be treated:
Brain disorders like Parkinson and Alzheimer thanks to derived brain cells
Diabetes thanks to derived insulin-producing pancreatic islet cells
Spinal cord damage thanks to derived nerve cells
Autoimmune disorders such as multiple sclerosis and rheumatoid arthritis thanks to derived cells of blood and bone marrow
In addition, it will help to save the lives of the thousands of people worldwide waiting for an organ transplantation by helping to create artificial organs. Not only is it difficult today to obtain an organ but even if organs are available many are being rejected by the body because of incompatability; let alone the brutal way some organs are being obtained, i.e. by buying them from people in third world countries or even extracting them without the donors consent ! Therapeutic cloning will eventually provide genetically 100% compatible organs such as livers, kidneys etc. and therefore save the lives of those who would perish without it.
Reproductive human cloning will help:
Infertile couples: we have received many requests from infertile couples who cannot have children even after years of infertility treatments. For those people cloning is the only way to have a child of their own genetic offspring.
Homosexuals: they cannot have a child today that is 100% related to them genetically but human cloning will provide this possibility for them.
Families who lost a beloved relative: human cloning can give life a second time to the same genetic code who has died at an early age for example.
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