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P.A. Levene
He studied nucleotides and determined the basic structure of nucleotides that make up DNA. Nucleoties are a subunit of nucleic acid, the two living forms are DNA and RNA. They consist of five carbon sugar, a phosphate group, and a nitrogenous base. -
Fredrick Griffith
The first major experirment that led to the discovery of DNA was preformed by him. In his experiment he studied two strains of bacteria that caused pnuemonia. Griffith tested these strains on mice. This experiment helped set a platform for the search to identify the reansforming substances. -
Oswald Avery
He went off of Griffith's experiment. He isolated different macromolecules of the killed S cells. Avery found out that when you introduces live R strand to the killed DNA of the S strand, the R strand changes into S strand. This led to futher experiments from other scientists debating wheather proteins or DNA were responsible for the transfer of genitic material. -
Erwin Chargaff
Chargaff analyzed the amounts of adenine, guanine, thymine, and cytosine in the DNA of various species In one experiment he discoverd that the amount of guanine almost equaled the amout cytosine, and that the amout of adenine almost equals the amout of thymine in a species. He used this to create a rule, C=G and T=A. -
Maurice Wilkins
Wilkns was in London, England working on a technique called X-ray diffraction. During this procces he used x rays and aimed them at DNA molecules. -
Rosalind Franklin
She came to work in the same place as Wilikins was. She also used the procces of X-ray diffraction. Here Franklin took a photo called, Photo 51. This was later used by Watson and Crick. In this photo, it is shown that DNA is in the form of a double helix. It is formed by two nucleotides twisted around each other. -
Hershey and Chase
They published experiment results that supported that the factor for genetic transformations was DNA. They used a virus that attacks bacteria. There was two components that made it ideal for what they were testing, the virus they were using contained DNA and protein and viruses cannot replicate themselves. They injected the genetic material into a living cell to reproduce. They used radioactive labeling to label each part of the bacteria to determind which part was the genetic material. -
Linus Pauling
Pauling proposed and idea of DNA being a triple helix structure. He over looked his design, the way it would have to be set up would self destruct, the molecules would repel from each other. This is ironic becaue he wrote a book about chemical bonds and he got it wrong. -
James Watson and Francis Crick
Watson and Crick used a photo taken by Franklin to made a modle of DNA. To make this they measured the width of the helix and the spacing of the bases. Some important features this showed were two outside strands consist of alternating deoxyribose and phosphate, cytosine and guanine bases pair to each other by 3 hydrogen bonds, and thymine and adenine bases pair together by 2 hydrogen bonds. This modle supported research from Wilkins, Franklin, and Chargaff.
