Examples of scientific method

Examples of scientific method

[http://www.sciencemag.org/feature/data/scope/keystone1/ Here] is an annotated example of this scientific method example titled "Microbial Genes in the Human Genome: Lateral Transfer or Gene Loss?".

DNA example

: Each element of scientific method is illustrated below by an example from the discovery of the structure of :*"DNA-characterizations": in this case, although the significance of the gene had been established, the mechanism was unclear to anyone, as of 1950.:*"DNA-hypotheses": Crick and Watson hypothesized that the gene had a physical basis - it was helical.:*"DNA-predictions": from earlier work on tobacco mosaic virus, Watson was aware of the significance of Crick's formulation of the transform of a helix. [Cochran W, Crick FHC and Vand V. (1952) "The Structure of Synthetic Polypeptides. I. The Transform of Atoms on a Helix", "Acta Cryst.", 5, 581-586.] Thus he was primed for the significance of the X-shape in photo 51.:*"DNA-experiments": Watson sees photo 51.

: The examples are continued in "Evaluations and iterations" with "DNA-iterations".

DNA-characterizations

: The history of the discovery of the structure of DNA is a classic example of the elements of scientific method: in 1950 it was known that genetic inheritance had a mathematical description, starting with the studies of Gregor Mendel. But the mechanism of the gene was unclear. Researchers in Bragg's laboratory at Cambridge University made X-ray diffraction pictures of various molecules, starting with crystals of salt, and proceeding to more complicated substances. Using clues which were painstakingly assembled over the course of decades, beginning with its chemical composition, it was determined that it should be possible to characterize the physical structure of DNA, and the X-ray images would be the vehicle. .."2. DNA-hypotheses"

DNA-hypotheses

: Linus Pauling proposed that DNA was a triple helix. Francis Crick and James Watson learned of Pauling's hypothesis, understood from existing data that Pauling was wrong and realized that Pauling would soon realize his mistake. So the race was on to figure out the correct structure. Except that Pauling did not realize at the time that he was in a race! "..3. DNA-predictions"

DNA-predictions

: When Watson and Crick hypothesized that DNA was a double helix, Francis Crick predicted that an X-ray diffraction image of DNA would show an X-shape. Also in their first paper they predicted that the double helix structure that they discovered would prove important in biology, writing "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material". " ..4. DNA-experiments"

DNA-experiments

: Before proposing their model Watson and Crick had previously seen x-ray diffraction images by Rosalind Franklin, Maurice Wilkins, and Raymond Gosling. However, they later reported that Franklin initially rebuffed their suggestion that DNA might be a double helix. Franklin had immediately spotted flaws in the initial hypotheses about the structure of DNA by Watson and Crick. The [http://www.pbs.org/wgbh/nova/photo51/ X-shape] in X-ray images helped confirm the helical structure of DNA ["The instant I saw the picture my mouth fell open and my pulse began to race." -- James D. Watson (1968), "The Double Helix", page 167. New York: Atheneum, Library of Congress card number 68-16217. Page 168 shows the X-shaped pattern of the B-form of DNA, clearly indicating crucial details of its helical structure to Watson and Crick.] . "..1. DNA-characterizations"

DNA-iterations

: After considerable fruitless experimentation, being discouraged by their superior from continuing, and numerous false starts, Watson and Crick were able to infer the essential structure of DNA by concrete modeling of the physical shapes of the nucleotides which comprise it. They were guided by the bond lengths which had been deduced by Linus Pauling and Rosalind Franklin's X-ray diffraction images. .."DNA Example"

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Scientific method — …   Wikipedia

  • History of scientific method — The history of scientific method is inseparable from the history of science itself. The development and elaboration of rules for scientific reasoning and investigation has not been straightforward; scientific method has been the subject of… …   Wikipedia

  • Scientific consensus — is the collective judgement, position, and opinion of the community of scientists in a particular field of science at a particular time. Scientific consensus is not, by itself, a scientific argument, and is not part of the scientific method;… …   Wikipedia

  • Scientific jury selection — Scientific jury selection, often abbreviated SJS, is the use of social science techniques and expertise to choose favorable juries during a criminal or civil trial. Scientific jury selection is used during the jury selection phase of the trial… …   Wikipedia

  • Scientific citation — is the process by which conclusions of previous scientists are used to justify experimental procedures, apparatus, goals or theses. Typically such citations establish the general framework of influences and the mindset of research, and especially …   Wikipedia

  • Scientific racism — denotes the use of scientific, or ostensibly scientific, findings and methods to support or validate racist attitudes and worldviews. It is based on belief in the existence and significance of racial categories, but extends this into a hierarchy… …   Wikipedia

  • Scientific visualization — A scientific visualization of an extremely large simulation of a Rayleigh–Taylor instability caused by two mixing fluids.[1] Scientific visualization (also spelled scientific visualisation) is an interdisciplinary branch of science according to… …   Wikipedia

  • Scientific misconduct — ] *Danish Definition: Intention(al) or gross negligence leading to fabrication of the scientific message or a false credit or emphasis given to a scientist *Swedish Definition: Intention(al) distortion of the research process by fabrication of… …   Wikipedia

  • Scientific modelling — Example of scientific modelling. A schematic of chemical and transport processes related to atmospheric composition. Scientific modelling is the process of generating abstract, conceptual, graphical and/or mathematical models. Science offers a… …   Wikipedia

  • scientific notation — noun : a method of expressing a number by giving only the significant figures within particular limits of accuracy and indicating multiplication by the proper power of 10 (as in 1.591 (10) 20) * * * a method for expressing a given quantity as a… …   Useful english dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”