Author: Karen Liu
Editors: Tharindi Jayatilake and Anand Soma
Arist: Karen Liu
Cloning—the process of producing organisms with identical DNA—seems very futuristic, but it has been happening in nature for a long time. Asexual reproduction in certain plants and animals, binary fission in bacteria, and identical twins are just a few examples. The world’s most famous clone, Dolly the sheep, was the first mammal to be cloned by an adult cell. Dolly isn’t the first-ever clone to be produced in the lab though, as several non-mammal animals were cloned as early as the late 1900s including salamanders and frogs. According to the National Human Genome Research Institute (NHGRI), there are three types of cloning: gene cloning, reproductive cloning, and therapeutic cloning.
Gene cloning, or DNA cloning, is the process of creating copies of specific genes. During this process, a genetic engineer first extracts DNA from an organism and uses enzymes to break the bonds between the nucleotides. Plasmids are then combined with these genes, which are then inserted into bacteria and prompted to multiply many times.
Reproductive cloning allows us to make duplicates of whole animals, which is the same process that created Dolly the sheep. It starts with a mature somatic cell, which is extracted from an organism. The DNA of this cell is transferred into an egg cell that has its DNA already removed. This egg cell is then cultured to start the reproductive process, and then finally implanted into the uterus of a female of the same species. Reproductive cloning and creating Dolly was crucial because it was the first animal to be cloned using a somatic cell rather than an embryonic cell. This advanced science as many scientists started developing stem cells from somatic cells.
Therapeutic cloning creates duplicate embryonic stem cells, which are used to create tissues that can repair or replace damaged tissues. Most embryonic stem cells are taken from the blastocyst, an embryo of around 100 cells is formed around the first five days an egg divides. Embryonic stem cells can develop into any type of cell in an organism, which is useful in growing healthy tissues, testing new drugs, and learning about diseases.
With all of this information about cloning, a very prominent question arises: Have humans been cloned? The answer is no. Despite the various claims that arose about human cloning, this idea is completely fictional. Most of the claims failed to provide evidence and were eventually disregarded. Part of the reason why humans haven’t been cloned yet is that it's much harder to clone humans than any other mammal. In human eggs, the spindle fibers - two essential proteins involved in cell division - are located much closer together than in those of other mammals. Thus, removing the egg’s nucleus and replacing it with another nucleus requires the spindle fibers to be removed, which interferes with cell division. Additionally, ultraviolet rays and certain dyes used to remove the nucleus can sometimes destroy the cell and prevent it from growing.
Although gene cloning is used widely in labs today, both reproductive cloning and therapeutic cloning raise many important ethical issues and are highly debated. For instance, reproductive cloning can offer opportunities for sterile couples to fulfill their dreams of parenthood. Others may use it to prevent passing on any harmful genes to their children. On the other hand, potentially creating a genetically identical human can “conflict with long-standing religious and societal values about human dignity, possibly infringing upon principles of individual freedom, identity, and autonomy,” according to the NHGRI. Likewise, therapeutic cloning offers treatment for the human disease at the expense of another life but in the process of therapeutic cloning, an embryonic cell is destroyed in the test tube. Is it ethical to collect embryonic cells even if it benefits those suffering from pain and disease?
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