PerspectivesAre you interested in submitting a Perspective Article? Be sure to read The Science Advisory Board's Editorial Guides for Perspective Articles. Click here. The Impact of the Discovery of the Structure of DNA by Juan Mendible, Ph.D. The impact of the discovery of the Double Helix structure of DNA is almost impossible to quantify. Right from the beginning, in the same paper in which the structure was published, was stated the following, "the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material." This statement immediately explained the resemblance between parents and offspring and divided the world of Molecular Biology into before and after the discovery of the Double Helix. The discovery of the structure of DNA was the keystone to more than a half-century of research that initiated a scientific revolution whose end is not yet in sight. Biology acquired a molecular and biochemical basis, and research into DNA brought forth new technologies that illuminated the complex chemistry of protein synthesis and reproduction. Four years later it led Sir Francis Crick to his landmark address to the British Society of Experimental Biology, entitled "On Protein Synthesis," in which he proposed ideas that proved of the greatest importance to DNA research. This paper became a classic of which Horace Freeland Judson wrote, "permanently altered the logic of Biology." To make a long history short, the discovery of the Double Helix started our deep understanding of Molecular Biology when Crick proposed that the principal function of genes —which, as he and Watson had suggested four years earlier, are contained in DNA— is the manufacture of proteins. Crick argued that genes appeared to control the orderly assembly of amino acids, as basic building blocks, into proteins. Consonant with the newly base-pairing structure of DNA, to understand protein synthesis, Crick proposed two general principles: • The Sequence Hypothesis: The order of bases in a portion of DNA represents a code for the amino acid sequence of a specific protein. Crick hypothesized that, with four bases to DNA and twenty amino acids, the simplest code would involve "triplets"—in which sequences of three bases coded for a single amino acid. Crick also formulated, for the first time, the basic organizing principle for research into genetic mechanisms. • The Central Dogma: Information is transmitted from DNA and RNA to proteins, but information cannot be transmitted from a protein to DNA. He discussed how information contained in DNA, from the nucleus of the cell, was transmitted to the site of protein manufacture in the cell's cytoplasm. With that proposition, Crick defined the agenda of Molecular Biology. This proposal led in 1960 to the discovery by Sydney Brenner, Francis Crick, Francois Jacob and Jacques Monod of messenger RNA (mRNA) and later on of tRNA. From a technical point of view, the understanding of how restriction enzymes and reverse transcriptase work and in consequence the birth of Genetic Engineering would have been next to impossible without the framework of the Double Helix. Neither would have advanced the comprehension of retrovirus replication, which has permitted the design of drugs to treat cancer and AIDS. The complementarity between DNA strands, or between DNA and the RNA it codes for, permitted the development of techniques that, even today, are of great help in Molecular Biology research and in the development of genetic tests, techniques such as Southern, Northern and by inspiration the Western. The understanding of DNA replication led to PCR, a technique that caused such a revolution that in less than four years after its design more than 10,000 papers in which it was used were published and that today is central in most genetic tests. All of these technologies based in the structure of DNA opened the door for the Human Genome Project (HGP) with its main promise of ridding the world of disease. It is only appropriate that it has been finished in the same year that the Double Helix becomes 50 years old. Fifty years later the Double Helix is changing Medicine. The HGP in turn gave birth to even more powerful technologies based on the complementarity of the strands: The microchips that allow the study of hundreds of genes or their expression. They lead to the discovery of genes or chromosome regions involved in or associated with diseases, such as phobias, hypertension, diabetes, etc. That is possible because we can compare the expression pattern of normal with abnormal tissues. Or that of a diseased tissue before and after a particular treatment. And what is more impressive, Genome-wide studies that permit the comparison of genomes between different populations and thus, look for disease causing genes conducting association and linkage studies at an scale never dreamed before. By comparing gene expression patterns of model animals such as mice and rats under different environmental conditions, scientists can pin-point chromosome regions that have their equivalents in the human genome and thus begin to understand the role that the environment plays in complex diseases such as hypertension. When all the problems that confront Gene Therapy have been worked out, the use of DNA as a drug will have an tremendous impact in Medicine by curing genetic diseases for which there is no other possible cure. This could be done even in uterus. Also, through genetic manipulation of stem cells it would be possible to repair tissue damaged by age, disease or accidents. All of those technologies have also shed an enormous amount of light on our understanding of evolution. By tracing genes and mutations through time and populations, they are reading our history. Early on Genetic Engineering led to the manipulation of plants, making some of them resistant to plagues and harsh environmental conditions, which could have a definite impact in decreasing or even eliminating hunger in millions of inhabitants of the underdeveloped world. Thus, the double helix, brought us Genetic Modified Organisms or GMO´s. From the HGP new sciences have been born; Functional Genomics or the study of how genomes functions, Pharmacogenomics (a part of which is Toxicogenomics), the design of drugs according to the patient’s genome, Bioinformatics, the application of Information Technology to understand how genes interact with each other and the environment, and Proteomics, the very ambitious study of how proteins interact in the cell to make it function. All the understanding of so many biological process brought about by the DNA is opening the gates for a science: Nanotechnology, which could revolutionize our understanding of Biology and disease process even more. All of those discoveries and technologies are part of Biotechnology - an industry that moves billions of dollars each year and is a constant source of new discoveries and numerous employments. The rapid advances in Biotechnology have produced a new discipline: Bioethics, which worries about the impact of Biotechnologies on environment, human rights and dignity. This is so, because left only to scientists, without the input from society, Biotechnology could also bring dangers to the world; dangers that could harm the future of humanity, such as germ line modifications or GMOs that could totally wipe out weaker organisms. It is difficult, if not impossible, to visualize the cascade of effects brought about by the discovery of the structure of DNA. Imagine all of those brilliant minds in all of those labs, which inspired by the Double Helix led to their gradudate and undergraduate students through the path of discovery. This path took us to the level of knowledge and understanding of gene function, gene expression regulation and gene utilization that we have today. This discovery also led to a whole industry, to new sciences and disciplines. It is not easy to name one particular aspect of life that is not or will not be affected by that discovery and its consequences. On a particular note, my life was changed when in Berkeley during my Ph.D. studies I was introduced to Molecular Biology, and today I can totally understand what is meant by a “Passion for DNA.” Take away the understanding of the compliment of the DNA strands and the whole castle, which I summarized here, will disappear. If I did not know that the chains are complementary how could I visualize and understand the rest? ### Dr. Juan Mendible has been a Science Advisory Board member since November 2001. He is a principal investigator at Universidad Central de Venezuela. Join an ongoing discussion of the importance of the discovery of the DNA helical structure with your fellow members on The Science Advisory Board Discussion Forum. ### << Previous Next >> [ View All Perspectives ] |
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