Cloning began with the idea that humans can be created from a single somatic cell without sexual reproduction. Ian Wilmut, a Scottish scientist, and his colleagues at the Roslin Institute wanted to announce the successful cloning of a sheep via a new technique that involved transplanting the genetic material of an adult sheep obtained from a differentiated somatic cell, into an egg from which the nucleus had been removed.
Cloning is a scientific technique for making exact genetic copies of living things and can involve genes, cells, tissues, or the whole animal. Some cloning already exists naturally, for instance, single-celled bacteria make exact copies of themselves every time they reproduce. While in humans, identical twins are similar to clones since they share almost the exact same genes.
The cloning technique has been ongoing for over 40 years using nuclei derived from non-human embryonic and fetal cells. The mitochondria contain DNA and reproduce independently. True clones have identical DNA in both the nuclei and mitochondria. However, the term clone can be used to refer to individuals that have identical nuclear DNA but different mitochondria DNA.
Reproductive cloning is the deliberate production of genetically identical individuals. Two methods are used for reproductive cloning, (a) cloning using somatic cell nuclear transfer. The procedure begins with the removal of the chromosomes from an egg to create an enucleated egg and replaced with a nucleus taken from a somatic cell of the individual or embryo to be cloned. The egg is then stimulated and can start to divide leading to the formation of a blastocyst, or preimplantation embryo that is then transferred to the uterus of an animal. This leads to further development culminating sometimes into the birth of an animal. The animal becomes a clone of the individual donor of the nucleus.
(b) Cloning by embryo splitting begins with in vitro fertilization, this is fertilization outside the woman’s body involving sperm and an egg to generate a zygote. The zygote later divides into two and then four identical cells. Afterward, the cells separate and develop into separate but identical blastocysts, which are implanted into a uterus. The DNA in the splitting embryo is contributed by germ cells from two individuals, the mother and the father who contributed the egg and the sperm respectively. Thus the embryos have two parents and their mitochondrial DNA is identical.
Although the clones are genetically identical the individual is not physically or behavioral identical since DNA is not the only determinant of these characteristics. They experience different environments and nutritional inputs while in the uterus thus would be expected to be subject to different inputs from their parents, society, and life experiences.
The importance of Cloning
Cloning especially human cloning can also be referred to as therapeutic cloning. The embryonic cells can be cloned to obtain organs for transplantation or for treating injured nerve cells and other health purposes. It is a technique that can be used to improve the genetic endowment of mankind for greater achievements such as in sports, music, arts, science, literature, politics, or of acknowledgment virtue. Therapeutic cloning enables the cultivation of stem cells that are genetically identical to a patient and the technique can be applied to reduce the risks of rejection by the immune system especially those affected by Alzheimer disease, diabetes, and spinal cord injury
The future of Cloning
DNA cloning is done in many genetics and pharmaceutical laboratories throughout the world for reproducing the particular types of cells, for instance, a skin or a liver cell to investigate characteristics. The human individual cannot be cloned but the genes can. The majority of animals that have been cloned such as mice, rats, goats, sheep, goats, and other mammals have a spontaneous abortion. The death of the fetus usually occurs closer to term. On the other hand, mammals or animals produced by cloning suffer from serious health handicaps such as early death, gross obesity, distorted limbs, or dysfunctional immune system and organs. However, the low rate of success in cloning can improve in the future through technological advances.