The Story About the Discovery of DNA

The development of the double-helix structure of deoxyribonucleic acid by James Watson and Francis Crick in 1953 was and is one of the most important scientific discoveries of our time. Essentially bringing to light the inner workings of human biology. However, though Watson and Crick were some of the only scientists working on the structure of DNA, at that time, many scientists before them had contributed important breakthrough discoveries in DNA function which led up to Watson and Crick's DNA structure discovery. Without them it is questionable as to whether Watson and Crick could have had enough knowledge of DNA to determine its double helix structure. This paper will discuss the earliest discoveries concerning deoxyribonucleic acid and the scientists who discovered them, followed by the formation and progression of the Human Genome Project, and the latest issues of genetic engineering.

According to Alters and Alters (2007), Friedrich Miescher, a Chemist in 1869, made the earliest scientific discovery relating to DNA (p. 127). Miescher noted the presence of a specific compound located inside the nucleus of the cells he observed, and stated that this compound was "acidic, phosphorus rich, and made of large molecules" (Alters & Alters, 2007, p. 127). The compound was aptly named Nuclein, named for its location inside the cell's nucleus, it would later be known as DNA. Also in the later half of the 1800's, a scientist by the name of Gregor Johann Mendel began experiments with plants, specifically pea pods, to observe his hypothesis of inherited traits among living organisms. Through the study of pea pod plants, Mendel was able to formulate three basic laws concerning the passing of traits from one type of species to another organism of the same species (University of Minnesota, 2003). Shortly after Mendel's observation, a scientist named Walter Sutton hypothesized a connection between the inherited traits of organisms, highlighted in Mendel's law, to the chromosomes located in a cell's nucleus. In 1910, Thomas Hunt Morgan was able to successfully prove Sutton's theory concerning an organism's hereditary material and their chromosomes citing an experiment he conducted involving fruit flies and their eye color.

Ten years later, in the 1920's scientist Phoebus Levene, who now called the nuclein, "Nucleic Acid," discovered two separate forms of nuclein. Alters and Alters (2007) note that, "Levene found that both types of nucleic acid are nearly identical in their makeup, each consisting of roughly equal proportions of three molecular parts: a phosphate group, a five-carbon sugar, and a nitrogen-containing base" (p. 128). These two forms of nucleic acid are called deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Later biological discoveries included evidence proving that DNA is an organism's hereditary material. The first round of proof was provided by Oswald Avery, Colin MacLeod, and Maclyn McCarty, the second round of additional proof was offered by Erwin Chargaff, and the final concluding round was supported by the work of scientists Alfred Hershey and Martha Chase (Alters & Alters, 2007, p. 128-129). The combined efforts of these teams of scientist brought about a new era of biological study in the area of DNA.

The work that followed was done on DNA's structural components. The initial discovery of the shape of DNA came from Rosalind Franklin and Maurice Wilkins. Franklin and Wilkins used X-ray diffraction pictures to observe the shape of DNA, and noted it to be in the shape of a helix, or helical coil (Lane, 1994). Following the helix discovery scientists James Watson and Francis Crick picked up where Franklin and Wilkins left off by building various models of the DNA helix to test the shape for accuracy. According to the "Genetics and Genomics Timeline" (1994), February of 1953 brought a revelation to Watson, "He recognized how two pairs of complementary bases would have identical shapes if held together by hydrogen bonds. The two long chains of such base pairs would likely form a double helix. The double helix model produced by Watson and Crick brought the two a Nobel Prize in the early 1960s. With the deoxyribonucleic acid mystery solved, and the shape successfully discovered, the task of decoding the human genes came into play.

The Human Genome project, an international effort to collect all possible DNA sequences found within the human genome, was initiated in 1990 and completed in 2003. This effort turned up a staggering 30,000 to 40,000 genes, an extremely large number, though not nearly as large as scientists initially expected ("What Was the Human Genome Project," 2007). The Human Genome Project made it possible for the exploration and creation of vaccines, the pre-determination of a child's genetics, and made it easier to diagnose adults and children with illnesses such as Down Syndrome and Sickle Cell Anemia caused by genetic defects. Lastly, The Human Genome Project brought scientists the power to dive into the world of genetic engineering. Although much of the work done during The Human Genome project was based on forming the human genome database, the project also collected agricultural gene sequences, which would aid in the newest biological development, molecular and genetic engineering ("Potential Benefits of Human Genome Project Research," 2006). The developments within the farming industry proved to be just as useful as the developments with the human genome.

Molecular engineering is the process of manipulating genetic molecules on a very small scale to create a new organism or plant. This process was made possible by the developments from The Human Genome Project and its branch discoveries of genome logging among plant and animal life. Wikipedia (2007) explains that genetic engineering involves an intricate process of "isolation, manipulation, and reintroduction of the DNA into cells or model organisms, usually to express a protein" ("Genetic Engineering," 2007). Genetic engineering technology allowed plants, and more specifically vegetables to be genetically engineered to improve productivity, and make the vegetable more resistant to various strains of disease that can infect the plant. Similarly, genetic engineering in farm animals has sought to improve the immune system of livestock and aid in improving the health and condition of the animals. In addition, by genetically modifying these animals and plants, scientists are essentially creating a new organism that is different from anything created by nature.

This technology however, has been met with some opposition. Health concerns for the people consuming the genetically modified livestock and produce has been a major issue. Pusztai (2001) explains, "When food-crops are genetically modified, one or more genes are incorporated into the crop's genome using a vector containing several other genes, including a minimum, viral promoters, transcription terminators, antibiotic resistace marker genes and reporter genes." While antibiotic immunity is a major concern, it is not the only concern associated with modified plants and animals. There are vast environmental implications to genetic engineering as well. The worry that modified animals could be released into the wild and breed, spreading the modified gene, is also a concern scientists are watching carefully (Alters & Alters, 2007, p. 173). In addition, wild animals that consume these genetically modified organisms could potentially be poisoned by the ingestion of "foreign genes," which could cause serious illness or even death ("Genetic Engineering Basics," 2007). If genetically modified creatures were to be released or escape into the wild it could have devastating effects of the current animal population; effects such as complete extinction of the species with the unmodified genes and repopulation with the modified species.

The biological world has come a long way since the first mention of cells, their content, and DNA; and a great many scientists have contributed their knowledge and resources to these groundbreaking discoveries. While there are controversies currently surrounding some areas of DNA application and research, the benefits of such knowledge clearly outweigh those of which we may still have doubts about. Gene replacement therapy, the diagnosis of genetic disorders and research to cure them, and disease research and vaccination development are only a few of the spoils of such significant discoveries concerning DNA. The discovery of our hereditary material, its structure, and the scientific applications of it, has expanded the world of biology and what man can accomplish in it.

References

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http://www.actionbioscience.org/biotech/pusztai.html

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