The DNA's double helix--the sub-microscopic core of our life--has been the subject of intense study and scrutiny for decades.
Observations and measurements at the scale of DNA are tricky. The distance between the rungs in DNA's ladder (or base pairs), for example, was thought to be barely over 3 millionths of a millimeter, or 3.4 Å (angstroms). And this ladder has been typically assumed to be very rigid.
But now a team of Stanford scientists, supported in part by the National Science Foundation, have used a novel molecular ruler to cast doubts on this picture. Using this molecular ruler, they marked each end of a snippet of DNA with electron-dense gold nanocrystals. These markers scattered X-rays directed at the sample differently than the rest of the molecules, and allowed for a more precise calculation.