User talk:DeeKayP

DNA: The Code of Life

Summary

Back even thirty years ago, the thought of creating a living copy of a higher form of life was considered science fiction. Now, science fiction has become science fact. In the Stargate SG-1 universe, members of SG-1 have encountered many advanced cultures and alien races which have mastered the art of creating copies of higher life forms, such as those of a human being. Although some of the methods imagined are still way out in the realm of science fiction, there are some elements of fact hidden behind the stories brought forth.

History of Cloning on Earth

Scientists created the most famous clone of a higher life form in 1997 with the birth of Dolly, the sheep clone. Dolly lived for six years, dying by lethal injection in 2003. Her lifespan was about half the usual for a sheep of her kind. She suffered from lung cancer and crippling arthritis. Scientists claim, however, that other than the cancer and arthritis, Dolly was normal. She was even the mother of six lambs, reproducing the "old fashioned way."

Dolly was produced by a method of cloning called "reproductive cloning." In this method, scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed. The reconstructed egg is treated with chemicals or electric current in order to stimulate cell division and once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth.

This method of cloning does not produce an identical clone of the donor animal. Only the clone's chromosomal or nuclear DNA is the same as the donor while some of the clone's genetic materials come from the mitochondria in the cytoplasm of the enucleated egg.

The source of Dolly's donor cell was an udder cell which was reprogrammed to generate an entire new organism, rather than just more udder cells. Scientists believe that errors or incompleteness in the reprogramming process cause the high rates of death, deformity, and disability observed among animal clones.

There are other forms of cloning practiced by our scientists today. One form of cloning is called "therapeutic cloning," or "embryo cloning." The goal of this process is not to create cloned human beings, but rather to harvest stem cells that can be used to study human development and to treat disease.

The form of cloning called "recombinant DNA technology," "DNA cloning," "molecular cloning," or "gene cloning" all refer to the same process: the transfer of a DNA fragment of interest from one organism to a self-replicating genetic element such as a bacterial plasmid (bacteria are the most often used host cells, but yeast and mammalian cells are also used). The DNA of interest propagates in the foreign host cell. This technology has been around since the 1970s and is a common practice in molecular biology labs today. Recombinant DNA technology is important for learning about other related technologies, such as gene therapy, genetic engineering of organisms, and sequencing genomes.

Stargate References

1.14 "Hathor"

Hathor rapes Daniel for his DNA

Hathor's hybrid larvae

The Goa'uld queen named Hathor, living in a female human host, extracted DNA, what she referred to as "the code of life," from Daniel Jackson in order to produce Goa'uld larvae which would be compatible with their future human hosts. She obtained Daniel's DNA through forced sexual intercourse and thus gained access to the genetic information encoded in his sperm cells.

Sperm cells were used by the Human Genome Project (HGP) to sequence human DNA. According to the documentation from this project, it is much easier technically to prepare DNA cleanly from sperm than from other cell types because of the much higher ratio of DNA to protein in sperm and the much smaller volume in which purifications can be done. Using sperm provides all of the chromosomes for study, including equal numbers of sperm with the X (female) or Y (male) sex chromosomes. However, HGP scientists also used white cells from the blood of female donors so as to include female-originated samples.

In her reproductive process, Hathor combined portions of Daniel's DNA into her offspring. The exact method is not known, but could be considered a form of gene splicing. She may have used one sequence of his DNA and duplicated, or cloned, it to produce her hybrid offspring, similar to the process of recombinant DNA technology of today, also called DNA cloning. The larvae, however, had mostly Goa'uld genetic materials.

Hathor's goal to create larvae which would not be rejected by a human host is similar to that of therapeutic cloning of today. The creation of genetically-modified pigs from which organs suitable for human transplants could be harvested is a potential of this form of cloning. The transplant of organs from animals to human is called xenotransplantation. Pigs have been cloned more successfully than primates, even though primates are closer to humans genetically-speaking. Scientists create something called a "knock-out" pig wherein they inactivate the genes that cause the human immune system to reject an implanted pig organ. The genes are knocked out in individual cells, which are then used to create clones from which organs can be harvested. In 2002, a British biotechnology company reported that it was the first to produce "double knock-out" pigs that have been genetically engineered to lack both copies of a gene involved in transplant rejection. The research is still ongoing.

All of the larvae that Hathor produced at the SGC base were destroyed by fire, but it was still possible for Hathor to have stored the necessary DNA fragments from Daniel's sperm in order to produce more larvae later. We are not made aware if she did, in fact, produce more larvae with Daniel's "code of life" after she escaped to Chulak or before she died in the episode, 3.01 "Into the Fire."

1.19 "Tin Man"

Daniel and his android clone

Totally within the realm of science fiction, the creation of SG-1's android doubles, or clones, was executed quite easily by Harlan of the planet Altair (P3X-989). These clones were produced by copying the likeness of each team members' physical form into a bio-mechanical body and then copying their consciousness—memories, behavior patterns, and feelings—in the android body much like artificial intelligence. Harlan also augmented each clone with the knowledge of the underground power station which sustained them, and with the ability to compute and think faster. Their bodies were also stronger and able to endure stress, such as jumping down over twenty feet without breaking anything. The androids were also capable of existing for thousands of years if they maintained their power source, their only form of nourishment.

These androids are not clones by the classical definition because they are not entirely biological. However, to the androids themselves, their bodies felt to them as if they were still human, but "better."

The android clones of SG-1 all perished in the episode, 4.21 "Double Jeopardy."

Episodes

• 1.14 "Hathor"
• 1.19 "Tin Man"
• 3.01 "Into The Fire Part 2"
• 4.21 "Double Jeopardy"

Related Characters

• Col. Jack O'Neill
• Dr. Daniel Jackson
• Capt./Maj. Samantha Carter
• Teal'c
• Harlan
• Hathor

Related Articles

• Goa'uld
• Symbiote

Further Reading

• The Gene School
• Human Genome Project: Genome Sequencing Fact Sheet
• Human Genome Project: Cloning Fact Sheet

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--DeeKayP 14:09, 2 Oct 2004 (PDT)