Commentary on Watson and Crick Dna Discovery Essay Example for Free

Commentary on Watson and Crick Dna Discovery Essay In their 1953 Nature publication, Watson and Crick announced their landmark discovery: DNA exists in the form of a right handed, three-dimensional double helix. They described their DNA model as two DNA strands connected by hydrogen bonds between complementary bases. Adenine bases are always paired with thymines, and cytosines are always paired with guanines. Watson and Crick identified the anti-parallel configuration of DNA strands; each 5 end of one strand is paired with the 3 end of its complementary strand. Nucleotides are linked to each other by their phosphate groups, which bind the 3 end of one sugar to the 5 end of the next sugar. Nitrogenous bases are available to participate in hydrogen bonding. This important structural feature correlates with function that would soon be discovered: the bases have sites available to form hydrogen bonds with the proteins that play vital roles in the replication and expression of DNA. Since its inception, these features of the Watson and Crick model remain the same today. This enduring credibility is amazing, considering that many scientific research findings are drastically modified over time. In this paper, the two scientists claim their model to be â€Å"radically different† in order to strongly set it apart from the DNA structural model that was competitively proposed by Pauling and Corey, and also by Fraser: a triple helix with bases positioned outward. Watson and Crick rejected the triple helix model, criticizing that the protruding bases would leave the negatively charged phosphates positioned inward and towards each other. This could not be the correct structure because the repulsion of negative charges would blow apart the helix. Therefore, Watson and Crick knew it was the bases, not the phosphates, which were positioned inward and linked by hydrogen bonds. Their structural hypothesis was consistent with Chargaff’s research as well as the x-ray data. The intrigue of this paper cannot solely be attributed to its clear and simple presentation of a landmark discovery. Watson and Crick were indeed scientific pioneers, but they could never have drawn correct conclusions about DNA structure without considering data and hypotheses of other scientists. Chargaff’s discovery about DNA base proportions as well as Franklin’s crucial X-ray crystallography data made it possible for Watson and Crick to derive the three-dimensional, double-helical model for the structure of DNA. Although other scientists came close, Watson and Crick were the ones who got it right. Watson and Crick’s model suggested the structure correlated with function: â€Å"It has not escaped our notice that the specific pairing we have postulated suggests a possible copying mechanism for the genetic material.† The process of DNA replication was unknown at the time. By investigation of its function in the replication process, scientists were able to find out more about the more complex levels of DNA structure, which Watson and Crick’s model fails to predict. Today, we know that there are different DNA structures in prokaryotes and eukaryotes. In eukaryotic cells, DNA in the nucleus is tightly packaged into chromosomes. The chromosomes form when DNA wraps around an 8-histone core to build the nucleosomes that make up chromosomes. Therefore, the double helix model of DNA is only relevant when DNA is in a replication stage. The model does not provide any information about important, higher level complexities of DNA structure. Our present understanding of storage and utilization of a cell’s genetic information has been possible because of Watson and Crick’s discovery. For example, understanding DNA has led us to new, successful avenues for medical research and treatment of diseases. We are able to use genetic screening for disease, and we have a better understanding of disease mutation, as in the flu virus. Also, our knowledge of DNA’s structure and function has made tissue matching possible for patients receiving transplants.