Cloning/Embryonic Stem Cells
The term cloning is used by scientists to describe many different processes that involve making duplicates of biological material. In most cases, isolated genes or cells are duplicated for scientific study, and no new animal results. The experiment that led to the cloning of Dolly the sheep in 1997 was different: It used a cloning technique called somatic cell nuclear transfer and resulted in an animal that was a genetic twin -- although delayed in time -- of an adult sheep. This technique can also be used to produce an embryo from which cells called embryonic stem (ES) cells could be extracted to use in research into potential therapies for a wide variety of diseases.Thus, in the past five years, much of the scientific and ethical debate about somatic cell nuclear transfer has focused on its two potential applications: 1) for reproductive purposes, i.e., to produce a child, or 2) for producing a source of ES cells for research.
Cloning for Reproductive Purposes
The technique of transferring a nucleus from a somatic cell into an egg that produced Dolly was an extension of experiments that had been ongoing for over 40 years. In the simplest terms, the technique used to produce Dolly the sheep - somatic cell nuclear transplantation cloning - involves removing the nucleus of an egg and replacing it with the diploid nucleus of a somatic cell. Unlike sexual reproduction, during which a new organism is formed when the genetic material of the egg and sperm fuse, in nuclear transplantation cloning there is a single genetic "parent." This technique also differs from previous cloning techniques because it does not involve an existing embryo. Dolly is different because she is not genetically unique; when born she was genetically identical to an existing six-year-old ewe. Although the birth of Dolly was lauded as a success, in fact, the procedure has not been perfected and it is not yet clear whether Dolly will remain healthy or whether she is already experiencing subtle problems that might lead to serious diseases. Thus, the prospect of applying this technique in humans is troubling for scientific and safety reasons in addition to a variety of ethical reasons related to our ideas about the natural ordering of family and successive generations.Cloning, or somatic cell nuclear transfer (SCNT), is the technique used to produce Dolly the sheep, the first animal to be produced as a genetic copy of another adult.
In this procedure, the nucleus of an egg cell is removed and replaced by the nucleus of a cell from another adult. In Dolly’s case, the cell came from the mammary gland of an adult ewe. This nucleus contained that ewe’s DNA. After being inserted into the egg, the adult cell nucleus is reprogrammed by the host cell. The egg is artificially stimulated to divide and behave in a similar way to an embryo fertilised by sperm. After many divisions in culture, this single cell forms a blastocyst (an early stage embryo with about 100 cells) with almost identical DNA to the original donor who provided the adult cell – a genetic clone.
OWN VIEWS:
The latest technological breakthrough in the field of medicine that would slow down the aging process among humans by injecting cloned cells from a young and healthy donor to repair and regenerate damage and dead cells of elderly recipients.