Watson and crick model of dna pdf
9.1: The Structure of DNA
Optimized geometries with B-DNA conformation were obtained through the inclusion of implicit water solvent and, in the DNA models, of sodium counterions, to neutralize the negative charge of the phosphate groups. The results obtained allowed us to compare the relative stability of isomeric single and double strands. Moreover, the energy of the Watson—Crick pairing of complementary single strands to form double-helical structures was calculated. This trend shows that the formation energy essentially increases with the number of hydrogen bonds per base pair, that is two between A and T and three between G and C. The DNA double helix results from several types of stabilizing but also destabilizing interactions between and within its two complementary, intertwined polydeoxyribonucleotide chains. Recently, there has been increasing effort in developing and applying quantum chemical methods able to reproduce the structure of native B-DNA and to correctly describe the energy involved in the intrastrand and interstrand noncovalent interactions between the nucleotide monomers.
Other scientists, such as Linus Pauling and Maurice Wilkins, were also actively exploring this field.
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DNA structure and replication
Watson-Crick Model of DNA
DNA is the largest macromolecule that represents the genetic material of the cell. Chemically, DNA is a double helix of two antiparallel polynucleotide chains. Each polynucleotide chain is a linear mixed polymer of four deoxyribotides i. In , J. Watson an American biologist and F.
This page has been archived and is no longer updated. In reality, this is not the case. Then, in the decades following Miescher's discovery, other scientists--notably, Phoebus Levene and Erwin Chargaff--carried out a series of research efforts that revealed additional details about the DNA molecule, including its primary chemical components and the ways in which they joined with one another. Without the scientific foundation provided by these pioneers, Watson and Crick may never have reached their groundbreaking conclusion of that the DNA molecule exists in the form of a three-dimensional double helix. Although few people realize it, was a landmark year in genetic research, because it was the year in which Swiss physiological chemist Friedrich Miescher first identified what he called "nuclein" inside the nuclei of human white blood cells.