How is x ray crystallography involved with dna

The X-pattern in the middle is characteristic of a helical molecule with regular repeats; the broad bands at top and bottom indicate the periodicity of the repeats. The photograph is of the highly hydrated B form of DNA , rather than the drier A form , which does not show a distinct helical structure. The photo does not, without mathematical analysis, indicate whether there are 2, 3, or 4 helices, which requires measurement of the intervals between elements of the X-pattern.

Rosalind Franklin - , together with her grad student Raymond Gosling - , made Photo 51 in May Maurice Wilkins - , working in the same lab group, with Gosling's assistance had previously made photos of the B form as early as Because the X-ray pattern is so regular, the dimensions of the helix must also be consistent.

For example, the diameter of the helix stays the same Maurice Wilkins obtained some of the first X-ray diffraction patterns of DNA from which dimensions could be calculated. Erwin Chargaff explain how he measured the levels of each of the four nitrogenous bases. DNA Structure 2. Transcription 3. Translation 8: Metabolism 1. Metabolism 2.

Cell Respiration 3. Photosynthesis 9: Plant Biology 1. Xylem Transport 2. Phloem Transport 3. Plant Growth 4. Plant Reproduction Genetics 1. Meiosis 2. Inheritance 3. Find more information on the Altmetric Attention Score and how the score is calculated. This method includes a historical account of the articles by James Watson and Francis Crick, Maurice Wilkins et al.

Throughout the X-ray diffraction analysis, excerpts of their articles are included to describe the obstacles encountered by these researchers, the contributions each person made to the determination of the structure of DNA, and the degree to which X-ray diffraction aided their determination of the DNA structure. The article is organized with the assigned problem as the main part of the text and the intermediate steps leading to the solutions given in the Supplemental Material.

Helpful hints and information are also given in the Supplemental Material. Writing the article in this way allows the project to be quickly implemented into upper-level undergraduate and graduate physics, chemistry, and materials science and engineering course curricula. View Author Information. Cite this: J. Article Views Altmetric -. Citations 8.