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Oswald Avery, Colin McLeod and Maclyn MacCarty destroyed different types of molecules to see if this affected an inherited change in bacteria. DNA was the only molecule that had an effect on transformation. These experiments led other sicientists to believe that DNA is the material of inheritance.
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He analysed DNA from many different species and found two things:
1. The proportions of cytosine and guanine were the same
2. The proportion on adenine and thymine were the same -
He showed that polypeptide chains are held together in the shape of an a-helix by hydrogen bonds, explaining that a similar strucure may explain why changes that occured in DNA when heated.
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They began working together to produce x-rays of DNA crystals but their differences meant that they had to stop working together. Franklin then went on the develop a way to obtain the highest quality X-ray diffraction pictures. This allowed her to work out positions of groups in the DNA molecules and eventually build up a two stranded helical model.
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They tried to work out the structure of DNA by gathering information from other scientists and creating a model that fitted all the facts. Maurice Wilkins gave them information about Rosalind Franklin's findings without her permission, giving them the final piece of evidence to confirm their ideas.
This is how the famouse doucle helix structure was formed!
