In 1953, Francis Crick and James Watson described the molecular shape of DNA as a "double helix." Double-stranded DNA is composed of two linear strands that run opposite to each other, known as ...

Later it was found that the sugar in nucleic acid can be ribose or deoxyribose, giving two forms: RNA and DNA ... in a helix as Franklin had found, but one going up and the other going down.

Here, travel into the tiny world of DNA, all the way down to the level of the atoms ... around a core of histones. Here is a view of the double helix -- the subject of Rosalind Franklin's Photo ...