Isu Kedokteran: Cloning

Isu Kedokteran, Cloning

Achmad Furqan Agussalim

A clone is an organism that possess the exact same genetic information as its original/ parental cell and can be formed naturally or artificially (1). Natural methods of cloning can be divided into three categories; for plants, animals, and bacteria. 

Plants can produce clones through propagation. A new copy of the same plant can be produced through propagation, which is when a small piece of a plant that has been cut, can regrow if replanted into the soil. Examples include cassava and roses. 

Propagated plants have several advantages, it is easier to regrow these type of plants as a small part of the parent plants needs to be replanted.

There is a misconception regarding self-pollination. Self-pollination is the process where a flower from a plant fertilizes another flower from the same plant, thus one might think that it would produce an exact copy of the plant, but due to crossing over and random orientation of the chromosomes, it will result in a similar but not exact same offspring. Bacterias can produce clones through a process called binary fission.

 It starts by replicating their DNA as well as plasmids, then its whole body, then splitting off into two same prokaryotes. In animals, clones can be produced naturally and artificially. Naturally, it can be produced through twins. 

There are monozygotic twins which is when a sperm fertilizes an egg which eventually splits into two, thus producing two exact offsprings with the same genetic sequence. 

On the other hand, dizygotic twins are formed when an unfertilized egg has divided into two then fertilized by two separate sperm, forming twins that share fifty percent of the same DNA (2). 

Another way of forming clones is through an artificial process called somatic cell nuclear transfer. 50 years ago, many would have thought that cloning animals would be impossible, but thanks to the modernization of technology we have gained a better understanding of the process and managed to clone several animals including sheep, dogs, and even camels. 

It begins by taking cells from a donor animal (cow 1), then the cells are grown in a culture while the nucleus of a mature egg cell is removed. Then the nucleus from the donor cell is placed within the empty mature egg. It is first stimulated in order to begin diving before placed in a surrogate mother (cow 2). After several months, a young cow with the exact same genetic sequence as cow 1 is born from cow 2 (3).