Human cloning and what it actually means?

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Image Source: Knoepfler lab stem cell blog, http://ipscell.com/2013/05/cloning/

We might look very similar to our parents or siblings and even grandparents but we are not clones of our relatives because we share some similarities of our genetic material or DNA with our parents and siblings, but not identical. Identical twins are the closest example of natural clones because the fertilized egg splits, creating two or more embryos that carry almost identical DNA

So, what is cloning actually? Cloning, in modern biology, means generating identical copy of a fragment of DNA molecule or a cell /organism containing identical genetic material as the donor or parent cell/organism.

DNA cloning is routinely performed in lab for better understanding the role of certain fragments of DNA like genes or regulatory region. First let’s understand how DNA can be cloned.   This is done by use of methods of recombinant DNA technology: recombinant meaning DNA from different organisms is recombined. In this process DNA to be cloned -"insert" is ligated to the "vector" DNA by ligase enzyme and put into a host cell like a bacterial cell that replicates this recombined DNA fragment. This generates many identical copies of the DNA fragment or clones of the insert DNA.

The next level is, can we clone an organism? Yes, we can. At the organism level, that is generating animals containing identical genetic material as the donor animals.

How is that done? Artificially, animal clones are generated by the technique of somatic cell nuclear transfer or SCNT. In this process, nucleus from a somatic cell of adult animal (donor) is transferred to an unfertilized egg cell whose nucleus is removed (enucleated recipient cell).

Why somatic cell and not the egg cell itself? The reason somatic cell is used because it has two copies of the genetic material/DNA. Germ cell that is egg and sperm has only one copy of the DNA (haploid-1N) and the other copy comes from the other parent during fertilization of the egg by the sperm resulting in the diploid (2N copies of genetic material) embryo. Hence, germs cells (1N) cannot be used.

Now that the recipient has the genetic material of the somatic cell, it has to be implanted into surrogate mother’s womb for the development of the embryo to a baby animal. This baby animal born will be a clone of the donor adult animal whose somatic cell was used. This is because it has the identical DNA as that donor. Dolly, the sheep, was the first animal to be cloned using this process. Following this method, several animals have been cloned (https://en.wikipedia.org/wiki/List_of_animals_that_have_been_cloned).

Is it possible to generate a human clone in the same way? Technically YES!! But there are several ethical issues regarding cloning a human. Why? It leads us to generate many clones of an individual or individuals having modified DNA as per our wish. This can turn dangerous because it can be used to propagate only certain traits that destroys the diversity we see in humans and this diversity has helped us to adapt and evolve as a species. This diversity also makes us unique and capable of achieving new things, as each individual can have unique possibilities and do unique things that can shape the progress of humanity. Rather than generating an army of say only Einsteins and Hitlers or even Frankensteins! Also, as this technology is extremely powerful and can be exploited both in good and bad ways - currently most countries DON’T ALLOW HUMAN CLONING. However, cloning of human genes has been used for therapeutic and reproductive purposes, with strict adherence to proper ethical guidelines and only by trained scientists.

 

Article by:

Parna Saha

Senior research Fellow (PhD)

CSIR-Centre for Cellular and Molecular Biology

Hyderabad – 500007

Email: parnasaha@ccmb.res.in

 

Posted By : ScienceIndia Administrator
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