The Process of Cloning
In the beginning of all life was a cell. The combination of two reproductive cell brings forth to an individual life contain inside the united cells. In reproduction the cell which belongs to the female is called oocyte, which is a term used to denote an egg cell which is not yet fertilized by a sperm cell. When fertilization takes place, the oocyte combines with the sperm cell and produces a “zygote”. Afterwards, the “zygote” would enter the process of cell division which later leads to cell differentiation. Cell Differentiation refers to the process by which the cells are able to develop into different other cells as specified in the blueprint or the so-called “DNA”.
The basic concept in cell biology that allows whole animal cloning to take place was the process of cell division. When cells began to divide they continue on making copies from a mother cell. It would produce two daughter cells that would later produce two other until there are yet too many to produce tissues, organs, etc. Since, each of these cells is a complete replica of the mother cell. It contains the same genetic make up that the mother cell posses in its nucleus. Without the nucleus the cell could not be able to perform its normal function and would stop dividing and differentiating.
This was the process that fascinates John Gurdon in 1960’s. He tested this experiment on frog’s oocyte. He carefully remove the nucleus from the oocyte. This, as expected have deterred the process of cell division and differentiation. In order to restore the functions, a donor nucleus was inserted to the oocyte. This is called nuclear transfer and thus, it would continue to function as a new cell. Commonly, the process was also known as serial transplantation.
The experiment had revealed that indeed, the process of cell differentiation could be stopped. That one can reverse the process since Gurdon does the experiment in a mature or adult cell. Having this knowledge, it opens the windows for other theories and hypothesis concerning cloning. Since, cell activity could be halt and then continued, it offers a chance for scientist to find what they could do with the cell.
The current method in animal cloning involves almost the same principle that Gurdon have used in his experiment. However, since the experiment of Gurdon is only effective on frogs and the oocyte which develops into tadpoles do not grow into frogs. There is a need for several reconsiderations, before scientists have been able to distinguish what shall be done.
First, scientists have looked back into the process of cell cycle as a whole. It is a continuous cycle that involves division, copying of DNA, growing into individual cells and back to division. However, there are certain cells such as neurons, which after sometimes would stop tentatively or permanently from the cycle. These cells are commonly referred to as quiescence. These cells were the one’s that Keith Campbell used in his experiment of “Dolly”, the first cloned sheep or mammal in general. The nucleus of the cell was again removed, and then a nucleus from a quiescent cell was injected. The nucleus was fused to the oocyte through the use of a faint electric pulse. This has triggered the cellular activities that restarted the process of cell division and cell differentiation. After this process, the cell was transferred to the uterus of another sheep. This process, according to reports has taken 276 times before being successfully completed.
Today, cloning is made through taking away a cell from a donor which is a female. Then, one would take another unfertilized egg cell from another female donor. Afterwards the nucleus would be removed from the egg cell. Then the somatic cell (cells excluding the egg cells and the sperm cells) nucleus would be transferred to the egg cell. It shall then be left for about a couple of hours or more in able to let the nucleus adapt to its new environment. A liquid chemical would be dropped on the egg cell in order to trigger cellular activities. When the cell has achieved cell division creating sixteen bunches of cells called “morula”, it would then be the time to insert the embryo into the “surrogate” mother. If the cloning would be successful, then a baby would be born, if not then one shall try again and watch over the mistakes that has been made.
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