Last updated: April 23, 2013
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".