Rosalind Franklin: DNA's unsung hero - Cláudio L. Guerra
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Years after her death, Brenda Maddox and Anne Sayre worked on biographies about Franklin and could clarify some aspects of her history that might otherwise have gone overlooked. Maddox’s work gave rise to an interesting documentary by PBS’ NOVA called Secret of Photograph 51.
Interested in learning more about early work on DNA? You can watch Watson's talk here: How we discovered DNA. Then check out the original Photo 51 here.
Franklin also did extensive work on crystallography - but what does this mean? Molecules like DNA are way too small to be seen by optic microscopes, and electron microscopes can't give a resolution that's good enough for us to see the structure of the molecules. In order to see these tiny details we can use x-ray crystallography. Crystals are solid materials in which the constituents are orderly arranged in a 3-D structure that repeats itself in all directions.
When crystallographers want to study a molecule, they take an x-ray of a crystal made from that molecule, pretty much like a doctor's or dentist's x-ray. The x-rays then interact with the atoms in the crystal, and because a crystal is a repeating pattern, the interaction is amplified many, many times. The resulting image is the sum of waves that are strengthened when they're in phase and weakened when they're out of phase. That way, the sum of positive interactions forms the final image and a computer program can calculate the positions of every atom from the positions of the dots.
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