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Rosalind Franklin - DNA

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  • DNA: deoxyribonucleic acid is the information "blue-print" of the cell. It is a nucleic acid and is made from building blocks called nucleotides. This genetic information is passed from parent to child... more
  • Double Helix: nucleic acid double helix is a biology term used to describe the molecule of DNA and RNA... more
  • Helix: a smooth spiral curve. Helices (plural) can be either right-handed or left-handed. Springs are an example of a helix... more
  • Nobel Prize: a set of awards given each year in Physics, Chemistry, Physiology or Medicine, Literature, and Peace. Named after Alfred Nobel who on his death gave most of his fortune to establish the prize... more
  • Posthumous: an honor or award given after someone has died.
  • RNA: an acid found in all living things that carries messages from DNA to the rest of the cell to be made into protein.
  • Scavenger hunt: a game where players search and gather items on a list.
  • Virus: a super tiny germ that you can only see with a microscope... more

It Was Like a Giant Scavenger Hunt

In the early 1950s biologists were searching for the answers to some of the most important science questions left unanswered. How is information stored inside living cells? Could there be only one way these instructions were packaged? If there is, what does it look like? How did it work? All of these questions were an important part of the biology and many scientists were racing to find the answers.

Rosalind FranklinThe answer came from a group of scientists who were working on their own projects as well as a few who were on a giant scientific scavenger hunt. James Watson and Francis Crick were two researchers who spent their time piecing together information that other scientists had published. They also spent time talking with scientists who were busy in their labs running experiments. One of these scientists was Rosalind Franklin. She was an expert in a technique called X-ray crystallography. Her work would hold the key to discovering the structure of DNA, the blueprint of life.

A scientist from a young age

At the age of 15, Rosalind Franklin decided she wanted to become a scientist. Her father did not like this at all, because it was not considered to be appropriate. Yet she was determined and stuck to her plan. It was not always easy though. From 1951 to 1953, Franklin worked at King’s College in London. Her gender and her upper-class background made life difficult. It seems that some of her colleagues sneered at the way she spoke. On top of this women were not even allowed to enter the senior common room. This made her very angry, because many male colleagues had lunch there. However, none of this stopped Rosalind Franklin from making crucial contributions to science.

Contributions to science

Rosalind Franklin used a technique called X-ray crystallography to find out the 3D shape of molecules. She applied this technique to different samples. Early in her career she worked on carbon and coal. Later she started working on biological subjects. She made major contributions to the discovery of the shape of DNA. After her work on this molecule, she also gave new insights into the first virus that was ever discovered: the Tobacco Mosaic Virus . She thought the virus might be hollow and only consist of one strand of RNA. Although no proof existed at that time, she turned out to be right. Unfortunately this was not confirmed until after her death.

Tobacco mosaic virus

Photo 51

In 1962, James Watson, Francis Crick and Maurice Wilkins got the Nobel Prize for the discovery of the shape of DNA. “Photo 51” was an X-ray diffraction image that gave them some crucial pieces of information. It was only after seeing this photo that Watson and Crick realized that DNA must have a double helical structure.

The problem was that Photo 51 was actually made by Rosalind Franklin. Maurice Wilkins, a colleague had shown this picture to Watson and Crick without even letting her know. This added to the tension at the time of the discovery of DNA. Unlike her colleagues, Franklin was not awarded a Nobel Prize for her contributions to this important discovery. She died in 1958 and the Nobel Prize cannot be obtained posthumously.

While a lot of Rosalind Franklin's work used X-ray crystallography she also used other X-ray diffraction techniques. Her famous image of DNA called 'Photo 51' was made using a  X-ray technique that did not require the sample to be in crystal form. She used this method since DNA, like some other big molecules, does not like to form a crystal. Instead, DNA prefers to form organized fibers. Photo 51 still shows the classic diffraction pattern, but in this case the sample still contained water and was not a crystal.

Rosalind Franklin - DNA - B form


References:

Janus, The Papers of Rosalind Franklin. Retrieved May 2012 from http://janus.lib.cam.ac.uk/db/node.xsp?id=EAD%2FGBR%2F0014%2FFRKN

Merry Maisel and Laura Smart, Science Women, Rosalind Elsie Franklin, (1997). Retrieved May 2012 from http://www.sdsc.edu/ScienceWomen/franklin.html,

David Ardell, Biotech Chronicles, Rosalind Franklin (1920-195), (October 25, 2006). Retrieved May 2012 from http://www.accessexcellence.org/RC/AB/BC/Rosalind_Franklin.php

Martha Keyes , Contributions of 20th century Women to Physics,  Rosalind Franklin, (May 16, 1997). Retrieved May 2012 from http://www.physics.ucla.edu/~cwp/Phase2/Franklin,_Rosalind@841234567.html

K. C. Holmes. Fiber Diffraction. (1998). Retrieved August 26, 2012 from http://homes.mpimf-heidelberg.mpg.de/~holmes/fibre/branden.html

David Goodsell. Molecule of the Month. January 2009. Retrieved August 30, 2012 from http://www.rcsb.org/pdb/101/motm.do?momID=109

Photograph of Rosalind Franklin and Photo 51: Ask A Biologist tries to insure proper permissions before posting items on this website. For these images we have not been able to identify or contact the current copyright owner. If you have information regarding the copyright owner, please contact Ask A Biologist using the feedback link in the gold box to the right.

Protein and virus crystals grown in space

A collection of protein and virus crystals including the satellite tobacco mosaic virus. All were grown in space. Click to view larger.

 

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