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Miescher
Miescher planned to to isolate and characterize proteins inside of white blood cells but found a substance in the cell nuclei that had a high phosphorus content and other chemical properties different from other proteins. He named this substance nuclein. At the time he did not know the importance of this substance -
Chargaff
Chargaff believed that living species were different because of the differences in their DNA. He looked for evidence in support this belief. Chargaff used partition chromatography to separate DNA into its components. Chargaff began to focus on DNA bases., Chargaff discovered that the proportions of bases in DNA depended on the species the DNA had come from, and that in any species the ratio of A:T is 1:1 and G:C is 1:1. -
Franklin
Franklin's x-ray diffraction image of DNA structure showed the true sturcture of DNA.Franklin was able to obtain two sets of high-resolution photos of crystallized DNA fibers by using x-ray crystallography. She used two different fibers of DNA, one more highly hydrated than the other. She was able to find the basic dimensions of DNA strands, and that the phosphates were on the outside of what was probably a helical structure. -
Hershey and Chase
The Two wanted to prove that genes were DNA. They conducted an experiment using bacteriophages. When bacteriophages containing 32P (radioactive), were allowed to infect nonradioactive bacteria, all the infected cells became radioactive. The DNA component of the bacteriophages is injected into the bacterial cell while the protein component remains outside. The DNA is able to direct the formation of new virus particles complete with protein coats.The experiment provided proof that genes are DNA -
Watson and Crick
Watson and Crick used cardboard cutouts to represent the four bases: A, C, G, and T and the sub-units of nucleotides. They tried to place the pieces together like a puzzle. Until they completely change the way of putting the puzzle together did they puzzle fit correctly. The structure also reflected Chargaff’s rule. They came to a conclusion: the DNA molecule is a three-dimensional double helix. -
Meselson and Stahl
There were three basic models for DNA replication that had been proposed by the scientific community after the discovery of DNA's structure. Meselson and Stahl did experiments by growing bacterium E. coli to test how DNA replication occurs. They found that DNA replicated semi-conservatively, meaning that each strand in a DNA molecule serves as a template for synthesis of a new, complementary strand.
