First Time Humans Saw the Structure of DNA - the photograph that revealed the Geometry upon which all Life is based.
Photo 51 is the nickname given to an X-ray diffraction image of DNA taken by Raymond Gosling in May 1952, working as a PhD student under the supervision of Rosalind Franklin. It was critical evidence in identifying the structure of DNA.
Working in the lab alongside Wilkins in 1952, Franklin had taken a startling, high-resolution photograph of a piece of DNA using X -ray crystallography, a technique whereby X -rays are shone on a crystalline structure (in this case, the DNA protein), to create a scattered reflection pattern on film.To the naked eye the photo looked merely like an X diced up into bits, but to Franklin it confirmed that DNA was a double-helix.
Photo 51 has an important place in history and has at least a claim to be the most important image ever taken.
The plan was to grow a single crystal from this compound for a single crystal X-ray crystallographic analysis to know the exact structure of the compound. But sadly it only gave these fluffy needle like crystals from every solvent what could be used for it’s crystallization.
An English chemist whose work with x-ray crystallography was instrumental to discovering the structures of DNA, viruses, coal, and graphite; she died of breast cancer before she could be awarded the Nobel prize, and her colleagues Watson and Crick are often given sole credit to this day
Ok so some of you remember the crystallization stuff from my field study that I posted
Well it turns out today I got to take a much closer look at
the crystals I made and shoot them through the X-ray machine.
So here’s one of the tubes with the MANY crystals of hemoglobin
(with the drug). I showed you something like that last week.
I got to use the microscope to look at them up close and pick a good enough crystal to shoot through the X-ray diffraction machine.
LOOK AT HOW FUCKING BEAUTIFUL THEY ARE
So the crystal we picked went under a glycerin/mother liquor solution to protect it from breaking down. (Below: the crystals on the left, the solution on the right, and the original mother liquor is behind the solution)
Mother liquor is the liquid leftover after a crystallization btw.
So the crystal was picked up with a really tiny “lasso” tool so it could be hooked up onto the X-ray machine.
That tiny, pointy thing has a REALLY small hoop at the tip of it to pick the crystal up.
here’s a pic of it up close; that’s how small the hoop and crystal is
and this is the X-ray diffraction machine.
The crystal is held up here:
and this “shoots” towards the crystal which lets it’s X-rays scatter and that gives us information on the crystalline structure. That ultimately lets us know about the structure of the individual molecules.
Here’s an up close look at the crystal that was picked:
That’s after it was mounted on the X-ray machine. It’s hard to see cause it’s in front of the black screen.
and that’s the “X-ray” of the crystal we got. The individual dots are the individual components of the crystal. (We actually diffracted a second crystal to get a better x-ray because the dots were too close together on this one). This basically lets us see each unit cell of the crystal itself which would contain a repeat of the hemoglobin molecule with the drug/compound in this case.
By next week, I’ll be able to take a look at the actual protein structure of the Hb molecule and the drug and see how they bind together.
Hodgkin (1910-1994) was a British chemist who in 1964 won the Nobel Prize for
her development of protein crystallography. She advanced a technique used to
determine the three-dimensional structure of molecules, and confirmed the
structures of penicillin and of the vitamin B12.
She is seen as a pioneer in the field of X-ray crystallography, and her
extensive work led to a better understanding of the structure of biological
molecules. Years after winning the Nobel, she was also able to decipher the
structure of insulin.
On February 21, 1953, Francis Crick and James Watson discovered the structure of deoxyribonucleic acid (DNA) using unacknowledged photographs and research by their colleague Rosalind Franklin. They had considered many other candidates for the structure, including single and triple strand helices before deciphering the structure. Franklin’s x-ray crystallography (image on right) would provide the missing essential clue they needed to decipher the structure. They would publish a paper that same year describing their discovery, but the significance of the discovery was largely overlooked by the general public for over a year. Today it stands as one of the most remarkable milestones in the history of science.
The word deoxyribonucleic is a compound word formed around the main root word ribose, which arrived in English in 1892 via the German word Ribose which was itself borrowed from the English word of 1880 arabinose, a sugar derived from gum arabic. The word nucleic comes from the Latin word nucleus meaning a kernal around 1700, from the Latin diminutive nucula meaning a little nut. It did not take the meaning of a central characteristic or attribute until 1762. It wasn’t applied to cellular structures for another 70 years around 1862. The -oxy- root comes from the Ancient Greek word οξυς (oxys) meaning sharp or pointed (sharing the earlier common root word that gave the Latin word acer with the same meaning and ultimately the English word acid). The de- prefix is a Latin preposition meaning down from, off or away from, used mainly in English compound words as a privative, meaning that something lacks something.
//Yo Yo guys, I just started a new blog dedicated to my crystallography, so please check it out and give it a follow for some beautiful and interesting chemistry! I will try to link it below. Fingers crossed, i’m not good at formatting posts. This shot is an early shot of one of Macke’s copper sulfate crystal clusters! Now a single crystal has been grown to a length of around 7-8cm. She has talent that girl and its a pleasure to work with her.//