The Photo 51

Believe it or not, this old abstract looking image, known just as Photo 51, is one of the most iconic images taken by humanity in its path to conquest of knowledge.  Let me explain.

One way science differs from religion is that when some scientist on his/her path to glory claims discovery of some wonder of the universe, hundreds of brilliant scientists around the world respectfully get busy, for their own glory, to prove it wrong.  Scientific discovery is hard.  

We humans, along with other animals, plants, bacterias, viruses, planktons, diatoms - all are made of something called Cell.  The building block of life.  But there is more to it.  By the early 1950s it was known to the scientists that within those slimy cell walls, inside its heart called the Nucleus - there is a very fundamental element that makes me ‘me’.  And you ‘you’.  And ‘me’ different from ‘you’, and every other lifeform in the world.  They called it ‘gene’.  

But no one knew how it looked!  Though scientists were enthusiastically, and also bit nervously, aware that they are very close to demystifying this object.  But who will be the first?  Who will claim the coveted ‘Nobel’ prize, as it was nearly certain for this discovery.  For it was known that there will be a world before this discovery, and there will be a world after this discovery.  

When you are looking inside a Cell, particularly inside the Nucleus of a Cell, you are looking at objects very very and very small.  In the order of a few nanometers.  The length of a single wave of visible light is in the hundreds of nanometers.  That means we can not see detailed and clear structure of the ‘gene’ using a normal microscope which uses visible light.  It is simply too small for light to bother.  So instead of light, scientists used X-ray to create diffraction patterns through a complex process.  But these patterns needed to be analyzed, theorized and processed with other data to determine the actual structure.  

In 1952, King’s College, London, a 26 year old Raymond Gosling made the above X-ray diffraction pattern image of a dna fiber working under his brilliant and industrious X-ray crystallographer supervisor Rosalind Franklin.  This was 51st in the list of photos taken, so was called Photo 51.  Franklin, though, will not be able to analyze her own image. Fellow British biophysicist Maurice Wilkins will show this diagram to young American molecular biologist James Watson, who was by then relentless in trying to uncover the mystery.  Watson seeing this picture was the ‘Eureka’ moment for humanity.  

By then it was anticipated that DNA has a helical structure.  What was not known is whether it is a double helix, or a triple helix, and many other surrounding details.  Looking at the Photo 51, James Anderson realized this is the diffraction pattern of a double helix.  DNA is a double helix strand.  Case closed!

James Watson was working very hard with experienced biologist Francis Crick in the famed Cavendish Laboratory in Cambridge to uncover the DNA mystery.  They were racing against the likes of Linus Pauling (USA) to be the first.  When James Watson saw the Photo 51, the race was over!

It took Watson and Crick some more time to formalize the model.  Mid-March 1953 they published a small paper which explained the final structure.  And just like that, DNA mystery was over.

In 1958 Rosalind Franklin died at the age of just 37.  In 1962 the rest of the crew got the Nobel Prize for their groundbreaking work.   In 1968 Watson wrote a book The Double Helix explaining the entire journey that led to the discovery of DNA structure.