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P.A. Levene
He determined the basic structure of nucleotides in DNA. He also found that the two nucleic acids in living cells are DNA and RNA. -
Frederick Griffith
Studied two strains of bacteria that causes pneumonia and found that one of the strands could be transformed into another form. One of the strands was coated in sugar and causes pneumonia. He had performed an experiment with mice and bacteria that shows a transformation of DNA. -
Oswald Avery
He identified the molecule that transformed the two strands of DNA. A similar experiment to Griffith's was performed by Avery. Oswald concluded that when one of the strands was killed, DNA was released. Some of the bacteria incorporated it's DNA into their cells and transformed into a different cell. He suggested that DNA was responsible for the transfer of genetic material and had transformed bacteria using DNA. -
Erwin Chargaff
He analyzed the amount of adenine, guanine, thymine, and cytosine in the DNA of several species. Some of his data was published in 1950. He discovered that the amount of guanine is equal to the amount of cytosine and the amount of adenine is almost equal to the amount of thymine in a species. -
Rosalind Franklin
She was hired to improve X-ray crystallography. X-ray diffraction can provide information about the shape and structure of a molecule.She made diffraction patterns of DNA and was able to calculate the dimensions of a DNA molecule. Her information was used to construct a 3d model of DNA. -
Alfred Hershey and Martha Chase
They provided information that proved DNA was a transforming factor. Also, they used radioactive labeling to trace DNA as it infected bacteria in their experiment. They concluded that DNA was responsible for a transformation in genetics and not proteins. -
Linus Pauling
He proposed a triple stranded helix structure for DNA. He said that the three stands were intertwined to form one DNA molecule. He had the phosphate groups of each DNA strand facing inward and nitrogenous bases facing outward. -
James Watson
He was partners with Crick and measured the width of the helix and the spacing of the bases. He built a model of the double helix. Watson also proposed important features of the molecule. -
Francis Crick
Partners with James Watson, measured the width of the helix and counted the spacing of the base. He also built a model of the double helix with Watson. -
Maurice Wilkins
Involved in a technique that aimed X-rays at DNA molecules. Wilkins indicated that DNA was a double helix structure. Said that DNA is genetic material of all organisms made up of two strands of nucleotides strung into a double helix.
