human cloning?

Hey, I’ve just finished my bio assignment. My topic was about human cloning. And i found it really interesting. Check this out…

The term ‘cloning’ is actually ambiguous. Cloning can refer to DNA cloning/recombinant, human cloning, etc. But this time i just want 2 focus on cloning that means producing genetically identical cells to donor cells. Cloning is classified into two: reproductive cloning and therapeutic cloning. They are similar in techniques, but only differ in purpose. Reproductive cloning is for creating human/organism, while therapeutic cloning is used to produce stem cells.

One technique used widely for cloning animals is somatic cell nuclear transfer (SCNT). It involves both an unfertilized egg (oocyte, found only in female) and a somatic cell (body cell e.g. blood cell, skin cell, etc. — mammary gland cell is used in Dolly). First, the nucleus of an egg is removed (enucleation). Then the nucleus of somatic cell is transferred to an enuleated egg using a small spark of electricity. If the experiment is successful, the cell begins to divide : zygote –> morula –> blastocyst. Blastocyst is a stage in which cells compose of inner cell mass and outer cell (trophoblasts). The cell is then implented to surrogate mother’s womb. The result is a cloned organism genetically identical to donor of somatic cell.

Therapeutic cloning uses the same technique. But when the cell divides into blastocyst, the inner cell mass is removed to be used for “growing” stem cells. Stem cells are differentiated cells which allow the creation of tissues or organs. For example, if u harvest skeletal tissue, u will get either blood or skeleton cell. So.. therapeutic cloning is believed to be benefit for people who are suffered from Azheimer’s disease, Parkinson’s disease, diabetes, and possibly other genetical problems.

But it doesn’t mean that cloning is 100% useful. In fact, many scientists found that the cloned animals showed abnormal gene expression, “large offspring sydnromes”, or even illness. It is also inefficient… 277 attempts to create Dolly.. that means it needs a large number of eggs.. woman is usually produce 1 egg per month. So hard, eh?

Oh yeah, one more thing.. claim that cloned human would be personally identical to an existing person cell is entirely wrong. There are two reasons to explain it. First, cloned human could grow in different environment and experiences with an existing person. Although they may be genetically identical, such differences may create dissimilar personalities. Second, the host egg, even though its nucleus (contain DNA) is removed, has mitochondrial DNA that carries genes. These genes may combine with the nucleus of somatic cell and create either similar small changes in DNA or abnormalities. Thus, any cloned organisms are not exact replica of the donor cell. Make sense, isn’t it?

Cloning also raises ethical and moral concern. The method used in therapeutical cloning is a bit controversial bcoz the embryo that could have grown into a baby is destroyed in order to create stem cells. So.. think about it again!

Fact about human cloning:

• A commercial company: Clonaid claimed that they have clone five babies between 26 Dec. 2002 – 4 Feb 2003. The first cloned human to be born is called Eve. But scientists do not believe their claims because they never showed any evidence….
• In the period of only 7 years following the announcement of Dolly, other cloned animals have also been born: pigs, calves, mice, cat, etc….
• Most countries oppose reproductive cloning, but many of them support therapeutic cloning.
• Many websites that I found support reproductive cloning. One of them is The Human Cloning Foundation.

Also.. this web is useful, it has a lot of pictures and animations: Genetics – Utah

So, do u agree of human cloning?