Cloning


Cloning refers to the processes used to produce a genetically identical copy of an organism. A clone has the same genetic makeup as the original organism. Natural cloning occurs through asexual production where a plant or animal produces a breed with its genetic makeup. Artificial cloning methods include gene, reproductive and therapeutic cloning. Gene cloning produces similar genes while reproductive cloning means producing similar copies of whole animals. Another kind of cloning, therapeutic, produces similar copies of tissues and stem cells, and is mostly used in case of injuries.

Animal cloning

Reproductive cloning processes are used in animal cloning. In this case, scientists use somatic cells from an animal such as skin cells. The DNA of the animal’s somatic cells is transferred to an oocyte or egg cells. The egg cell used is empty as its nucleus carrying its DNA is removed before the new somatic cells are transferred. The somatic cells of the donor animal can be injected into the empty egg cell using a needle. Electrical current can also be used to fuse the somatic cell with the empty egg cell. The resultant embryo is first placed in a test tube and later transferred into the womb of a surrogate female animal. The surrogate animal carries the embryo to full term and gives birth to an animal with the same genetic makeup as the donor animal. The surrogate mother may feed the newly born clone.

Scientists began their cloning tests using mice. They managed to clone mice successfully and used the same procedures to clone sheep, cows and chicken. Scientists have cloned other mammals that include a cat, mule, dog, beer, rat, rabbit, monkey and an ox. Clones are not always identical to the donor animals but their genetic makeup is identical.

Human cloning

After cloning several animals successfully, scientists have been trying to clone human beings. The same reproductive cloning procedure is used to created human embryos with the same genetic makeup as the donor. However, despite several claims of several clones of human embryos, no evidence exists of such cloned embryos. Scientists in different parts of the world have made public announcements of test tube embryos but none exists. Some have withdrawn their claims after their experiments with human clones fail. The location of spindle proteins in humans complicates cloning processes as the process of removing the nucleus with the DNA components from the recipient egg cell removes the essential spindle proteins. In addition, the procedure sometimes destroys egg cells instead of removing the DNA components. Many religions oppose human cloning but scientists have continued with their research and attempts on primate cloning.


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