In the 1940’s, scientists began to suspect that the molecules responsible for heredity were not proteins, but in fact DNA. [5, 6]
King’s College London, Molecular Biologist Rosalind Franklin and graduate student Raymond Gosling, around May 6, 1952, took an x-ray diffraction image, photograph 51, of DNA fibre, revealing the “interesting orientation of the molecule deoxyribonucleic acid”. This image became the “critical piece of evidence leading to the identification of the structure of DNA” as a double helix. [1, 2, 3]
Watson and Crick, who began collaborating in 1951, used Franklin’s image (passed secretly to them by Wilkins) to develop their 1953 double helix, structural model of DNA from studying Linus Pauling‘s work [10]. On April 25, 1953 Watson and Crick published their proposed DNA model in Nature, briefly mentioning Franklin. [4, 7, 9]
In 1955, the enzyme DNA polymerase was isolated. “In modern molecular biology labs, purified DNA polymerase is used routinely – to copy DNA by PCR (the polymerase chain reaction), for various recombinant DNA techniques, and to run sequencing reactions.” [8]
In 1962, after Franklin´s death, Watson, Crick, and Wilkins shared the Nobel Prize in Physiology or Medicine for their findings about DNA’s molecular structure and explaining “how the information contained within genes is preserved through generations”. The reason for Franklin’s exclusion of any credit is unclear.
In 1961 mRNA was discovered as the intermediary molecule that takes genetic information from DNA in the nucleus to the protein-making machinery (ribosomes) in the cell cytoplasm – thus answered the question of how proteins were synthesised.
In 2009 the FDA stated the “discovery of DNA opened the door to a new science – human gene therapy.…”New vaccines are being developed and modified as new discoveries teach us more about the human immune system….Infectious diseases, both new and old, create an urgent demand for the hastened availability of new drugs.”