1943: X-ray Diffraction of DNA
William Astbury, a British scientist, obtained the first X-ray diffraction pattern of DNA.
X-ray diffraction patterns of crystallized molecules can reveal their structures with atomic precision. Astbury obtained X-ray diffraction patterns of uncrystallized DNA. He extracted DNA from cells, then dipped a needle into the viscous DNA solution and dragged out a strand containing many molecules lined up roughly parallel to each other. The X-ray diffraction patterns off this strand revealed that DNA must have a regular, periodic structure. He suggested that the nucleotide bases are stacked on top of each other "like a pile of pennies".
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Last Updated: June 22, 2007