What did Watson and Crick postulate?

James Watson and Francis Crick were both scientists who were researchers. Many scientists before them had laid down the foundations to the overall discovery of DNA, but Watson and Crick’s work was to identify the actual structure of DNA.

They initially used the work of another leading researcher, Rosalind Franklin who had taken photographs of DNA x-ray crystallography. Unfortunately before she could further this research she died of cancer. But her work was present:

The picture shows the results of her work. Crick and Watson were able to determine from this that DNA had a double helix. You can see in the picture that the organic bases have different numbers of rings separating the purines with pyramines, knowledge that they would use later on.

Using this newly found knowledge they published papers about their findings and ideas. For their work they received the noble prize, and their findings are pretty much undisputed worldwide.

According to their findings they proved that the DNA was a double helix bond, and not only that but there was a pattern in the way the different organic bases linked the helix strands together. This discovery was groundbreaking. Although scientists had realised the genetic importance of DNA and its hereditary abilities they hadn’t really discovered its structure.

They found out that the different organic bases ...

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Using this newly found knowledge they published papers about their findings and ideas. For their work they received the noble prize, and their findings are pretty much undisputed worldwide.

They found out that the different organic bases have a set pattern that was present in all the tested DNA strands. The four organic bases present in DNA, Adenine, Guanine, Cytosine and Thiamine were in a set pattern. Using the results of another scientist they found that the amounts of the organic bases were equal in number meaning there must be a relation to this fact. They found this out.

Adenine = Thiamine

Guanine = Cytosine

Cytosine = Guanine

Thiamine = Adenine

They also discovered the bonding system of these organic bases. They found that adenine to thiamine had 2 hydrogen bonds, whilst cytosine to guanine had 3 hydrogen bonds. All this information added together helped further to complete the picture of the DNA structure. Crick then though that DNA passed its information to Ribonucleic Acid (RNA), and this was then used in the synthesis of specific proteins. He was correct once more.

They carried out many complicated experiment to find out further about the structure. They mutated samples of DNA using bacteriophage T4, a virus. The mutations changed individual bases, as I mentioned above, in the DNA. When two or four mutations were together, the gene was still inactive, but when three mutations were put together in the same gene, the gene started to work again. This meant that genetic code was a triplet code. They had proven that there was three bases code for one amino acid.

Their work can be seen in the science museum in London, somewhere that I have been with the school. Their original model of the double helix is present there, they even labelled the organic bases showing their theory of complimentary pairing. The picture to the level shows their model, the first model to show the double helix.