What is cloning / Clones ? (Biology)
Clones or cloning is an artificial manner of production, where an identical genetic copy of an organism is produced. A clone is a genetically identical offspring of one parent. In this sense is always cloning humans intervention; although many plants spontaneously reproduce asexually genetically identical offspring is usually not clones (verb) called; it is an organism arise as a clone (noun) of the parent. Some lower organisms, such as protozoans, plants exclusively produced by cell division in which two identical clones arise, even the verb cloning is not used here.
Types of cloning
Natural clones
Cloning has been done for centuries in plants. This relates to plants or crops that are propagated vegetatively by cuttings, grafting or budding. Also, increasing the number of bulbous plants, or stem, and root vegetables, such as potatoes and narcissi, can be regarded as the cloning of a crop.
Reproductive cloning
Reproductive cloning, the cloning with the intention to create an identical clone, which can grow into a full organism. The most classic method of reproductive cloning, embryo splitting. Thereby becomes an embryo physically divided in two and the result is just the same as with identical twins. The founder of this technique is the German embryologist Hans Spemann and Nobel laureate.
The modern technique of cloning is nuclear transfer. This technique is also called "Somatic cell nucleus transfer (SCNT). In addition, the nucleus of a mature cell from the genetic mother in vitro is inserted into an enucleated oocyte, which is then introduced into the uterus of a surrogate mother. In this way, the reproduction is bypassed through germ cells. All of the genetic material of the clone derived from one parent. The first was suggested this technique Hans Spemann, although he himself never performed.
The first mammal which was cloned using this technique was Dolly the sheep in 1996. After Dolly were for example rats, mice, goats, cows, pigs, rabbits, cats, dogs and monkeys cloned. This is certainly not without problems. The cloning technique is inefficient, most cloned embryos and fetuses die during pregnancy. Many of the cloned animals did not appear to be healthy. They include members of defects in the immune system, fertility problems, obesity, respiratory and circulatory problems, kidney and brain disorders, diabetes, enlarged tongues, distorted faces and legs prematurely die from pneumonia, liver disease and cancer. One possible explanation lies in the fact that they have shorter telomeres at birth. Cloning also involves a lot of suffering.
To date, the most important practical application of the cloning of animals the multiplication of animals which are hereby at the same time by means of genetic engineering are genetically modified. A combination of genetic engineering and cloning makes it possible to very precisely to turn off a gene or adding, enabling fast transgenic animals can be made. For example, there are pigs made more suitable for xenotransplantation and cattle who can not get mad cow disease. Meanwhile, starting in the US to get the first products from cloned animals on the market, including meat or meat from cloned animals is called.
The cloning of organisms is often confused with the exact copy of these organisms. However, this is not the same. A clone is an exact copy, but a genetic copy of the original. When clones are stem cells extracted from the parent organism, which then again continue to develop into a foster mother. If, for example when using a cell donor animal of 10 years the clone at birth will be as developed as a "normal" young animal that has just been born. Thus, the clone is not exactly 10 years old.
Therapeutic cloning
Therapeutic cloning is clones with the intention to produce cells of the body that can contribute to the healing of certain diseases. This is primarily intended to heal people. Therapeutic cloning is still an experimental technique.
In therapeutic cloning, is a cultured embryo with the aid of nuclear transfer which is genetically identical to the patient. If the embryo is large than about one hundred cells, stem cells are removed and placed in culture. By manipulating the culture conditions, the stem cells can grow into any desired cell type. These newly formed tissues are then implanted into the patient in order to cure this disease are of (Stem Cell Therapy). The advantage of this technique is that the patient receives cells which are genetically identical to his own cells, whereby an immune response of the body is prevented (as opposed to xenotransplantation)
The availability of human oocytes, in part because they are relatively difficult to isolate, hereby forms a big problem. It was also found from animal studies that makes the embryo is a high risk of malformations, since the nucleus of the egg cell is still significantly different to that of a somatic cell. The shortage of human eggs can be collected by use of enucleated animal oocytes. But since mitochondrial DNA still remains, can cause later problems during the production of mitochondria. This problem can be possibly accommodated by co-transplantation of mitochondria of the donor. The Dutch Embryo allows embryos left over from IVF treatment to be used for scientific research for therapeutic cloning. However, the Dutch law forbids the cloning of human cells for both therapeutic and for reproductive use.
Human Reproductive Cloning
Human cloning, according to the prevailing scientific insights not possible, but it seems only a matter of time.
Human cloning is banned in many countries because of ethical concerns. In the Netherlands, says the Embryo of June 20, 2002 commented: "It is forbidden to perform actions with gametes or embryos with the intention of the birth of genetically identical human individuals" (Article 24, paragraph f).
In the ethical debate on human cloning concerns include the welfare and health of the clone. In animal cloning is already a high risk of spontaneous abortions and malformations. So at human cloning (a technique that is much harder and to date not even possible yet) it would be logical that there is much chance of spontaneous abortions and malformations. And besides, there are not only risks to clone itself, but there are also risks involved for the surrogate.