Creating genetically identical copies of biological matter is called the process of cloning. Genes, cells, tissues or the entire organisms are cloned by using the cloning techniques. Coning is the technology of biology which has made things possible which a person could imagine in his dreams or it seemed to be a science fiction. But now the technology of cloning has allowed making genetically identical organisms, plants, cells or tissues. Some tissues are also made through cloning. In the next decade, cloning will make it possible to improve the livestock production or plant production.
Types of Cloning:-
There are some types of cloning which are as follows;
This type of cloning involves the making of identical copies of DNA molecules. It is also called as gene cloning.
This type involves making of identical organism from another organism. Organism cloning is also called as reproductive cloning.
Production of stem cells through human embryos comes under this branch. Stem cells are extracted and embryos are destroyed.
Techniques of cloning:-
Cloning techniques are actually the processes performed in laboratory and are used to make genetically identical individuals similar to the donor parents. Cloning can also take place through artificial methods. Animal clones are produced through the process called somatic cell nuclear transfer.
Somatic Cell Nuclear Transfer:-
Somatic cell nuclear transfer is defined as, the transfer of the nucleus from the somatic cell to the cell of an egg. Somatic cells are taken from any part of the body and they are other than the sex cells or germ cells. For example blood cell, heart cell, lung cell or skin cell. In this technique the somatic cell nucleus is removed from its original cell and inserted it into the cell of an unfertilized egg, the nucleus of which is already removed. This egg along with its foreign nucleus is nurtured in the laboratory and when it transforms into an embryo, it is transferred into the substitute mother where it develops and reproduces into an individual. There are two variations of this technique, Roslin technique and Honolulu technique.
The Roslin Technique:-
Roslin technique is the alternative or variation of the somatic cell nuclear transfer. Researchers developed this technique at the Roslin institute. This was the technique through which dolly was born. In this technique, somatic cells along with their nuclei are grown in the laboratory and then these cells are deprived from nutrients to bring the cells into suspended stage. An egg cell whose nucleus is already removed is brought in close proximity to a somatic cell. Shock is given to both of the cells through electric pulse. This shock brings both the cells together and they fuse with each other to form an embryo. The embryo is then allowed to transfer into the mother.
The Honolulu Technique:-
This technique was developed by Dr. Teruhiko at Hawaii University. This method is quite different from the first technique. In this technique, nucleus of the somatic cell is taken and is inserted into the egg, nucleus of which is already removed. This egg is bathed with the chemical solution and develops into an embryo. Then this egg with foreign nucleus is transferred into the mother.
Researchers are very hopeful in using these techniques and finding cures for many diseases. These techniques are not only helpful in treating human diseases but also in genetically altering animals to produce human transplant organs.
Cloning of Dolly Sheep:-
Dolly was the first mammal which was produced through cloning process by using the somatic cell nucleus under the process of somatic cell nuclear transfer. She was cloned by scientists at the Roslin Institute. She lived until the age of six and died because of the lung cancer and severe Arthritis.
Following are the basic steps which were used to clone Dolly sheep.
1) First the nucleus extracted from the somatic cell of an adult sheep. Complete genetic information is present in that nucleus. This process is repeated many times to get many nuclei from many somatic cells. The nucleus was removed from the cell by using small needle or syringe.
2) Unfertilized egg was extracted from the sheep and its nucleus was removed. The egg contained half of the genetic information of the sheep. Very small needle or syringe is used during this process. During cloning process, many eggs are needed because all the eggs do not survive during the complete process.
3) Extracted somatic cell nucleus was then inserted into the unfertilized egg which is also without nucleus. Egg also contains all the traits of genetic material from its donor. The egg became identical to the donor parent.
4) This egg with foreign nucleus was placed into the womb of a sheep. The egg started developing into an embryo. When the child produced during this whole process, it was identical or clone of the donor sheep.
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