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P.A. Levene
P.A. LevineIn the 1920s he determined the basic structure of nucleotides that make up DNA. Nucleotides are the subunits of nucleic acids and consist of a five-carbon sugar, a phosphate group, and a nitrogenous base. He found out that the two nucleic acids found in living cells are DNA and RNA. -
Fredrick Griffith
Frederick GriffithHe performed the first major experiment that led to the discovery of DNA as a genetic material. He studied two strains of the bacteria Streptococcus Pneumoniae. He found that one strain could be transformed, or changed, into the other form. This experiment set the stage for the search to identify the transforming substance. -
Oswald Avery
Oswald AveryIn 1944, Oswald Avery continued the experiment started by Fredrick Griffith and identified the molecule that transformed the R strain of bacteria into the S strain. He isolated different macromolecules, such as DNA, proteins, and lipids from killed S cells. He concluded that when the S cells in Griffith's experiment were killed, DNA was released. -
Erwin Chargaff
Erwin ChargaffHe analyzed the amount of adenine, guanine, thymine, and cytosine in the DNA of various species. He found that the amount of guanine nearly equals the amount of cytosine, and the amount of adenine nearly equals the amount of thymine within a species. Known as Chargaff's rule: C=G and T=A. -
Rosalind Franklin
Rosalind FranklinShe took the famous Photo 51 using X-Ray Diffraction that indicated that DNA was a double helix, or twisted ladder shape, formed by two strands of nucleotides twisted around each other. She determined that DNA is the genetic material of all organisms. -
Maurice Wilkins
Maurice WilkinsFirst one to use X-Ray diffraction to study DNA while working at King's College in London, England. -
Linus Pauling
Linus PaulingHe formulated a model for the structure of hemoglobin in which atoms were arranged in a helical pattern, and applied this idea to proteins in general. -
Hershey and Chase
Hershey and ChaseAlfred Hershey and Martha Chase published results of experiments that provided definite evidence that DNA is the transforming factor. They used a technique called radioactive labeling to trace the fate of the DNA and protein as the bacteriophages infected bacteria and reproduced. -
James Watson and Francis Crick
James Watson and Francis CrickBuilt a model of the double helix that conformed to the others' research.
