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The Study of DNA
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P. A. Levene
In the 1920s, P. A. Levene determined thee basic structure of nucleotides that make up DNA, which is a nucleic acid. He concluded that deoxyribose, a phosphate, and 1 of 4 nitrogenous bases (adenine, guanine, cytosine, or thymine) make up DNA's nucleotides. -
Frederick Griffith
Frederick Griffith performed the first major experiment that led to the dicovery of DNA in 1928. Studied two strains of bacteria and found one strain that does not cause pneumonia can develop into the strain that does cause pneumonia. -
Oswald Avery
In 1944, Oswald Avery confirmed that Frederick Griffiths "transforming cell" was DNA. He isolated different macromolecules (DNA, lipids, and proteins). Eventually, he concluded that it was the DNA of the pneumonia-causing cells that was incorporated into the -
Erwin Chargaff
Erwin Chargaff analyzed the amount of adenine, guanine, cytosine, and thymine in different species' DNA. He found that the amount guanine is almost equal to cytosine and the amount of adenine almost equals the amount of thymine in all species. -
Hershey and Chase
In 1952, Alfred Hershey and Martha Chase discovered that viral DNA was injected into cells in order for viruses to reproduce. Viruses can not replicate themselves, so Hershey and Chase observed a virus closely to find that DNA was what aloud viruses replicate in cells. -
Linus Pauling
In 1953, Linus Pauling disocivered what he thought was the structure of DNA. He concluded that DNA was a triple-helix structure, while in reality, it was only a double-helical structure. -
Maurice Wilkins
In 1953, along with his assistant Rosalind Franklin, Wilkins helped to make the X-ray diffraction picture of DNA. -
Rosalind Franklin
Rosalind Franklin's photo of DNA and her data of X-ray diffraction helped Watson and Crick to determine that DNA has a double-helical structure. -
James Watson
Using Franklin's X-ray diffraction and with the help of Francis Crick, Watson measured the structure of a DNA and discovered it was a double-helix. -
Francis Crick
Along with Watson and the use of Franklin's diffraction picture, Crick also helped determine the double-helical structure of DNA. He also helped write a letter to the journal Nature meant to prove their structure hypothesis.
