So cool! Italian scientists have “seen” a double helix in higher resolution than ever before. But wait a sec, didn’t Rosalind Franklin do that half a century ago? Here’s the deal:
DNA is smaller than the wavelength of visible light. It is, by definition, invisible to us. But by using wavelengths that are even smaller than visible light, like X-rays, we have been able to discern some of the chemical structure of DNA and other molecules. That X-ray technique gave us Rosalind Franklin’s iconic X-in-an-O image that led to the discovery of the double helix.
But when we use X-rays, we are really looking at a sort of reflection pattern (or more accurately, “diffraction”) of the rays bouncing off of the atoms that make up DNA, not the DNA itself. It’s like trying to figure out the shape of a hand by looking at shadow puppets.
The Italian scientists imaged DNA closer than ever before by dehydrating the double helix onto microscopic silicon pillars, and then shooting it with a beam of electrons. Where the electrons hit the DNA, we see its shape, like a normal camera, just using electrons instead of visible light.
You can even see the fuzzy little notches of the base pairs!
(Read more about it at The Atlantic)