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P.A. Levene
P.A. Levene determined the basic structure of nucleotides that make up DNA.He stated that the DNA molecule consisted of a string of nucleotide units linked together through the phosphate groups, which are the 'backbone' of the molecule. Even though his ideas of structure of DNA were wrong, his work helped determined the structure of DNA in later work. -
Fredrick Griffith
He studied two strains of pneumococcus bacteria and found that one strain can be transformed into the other form. This suggested that that bacteria are capable of transferring genetic information. -
Oswald Avery
Oswald and his partners identified the molecule that transformed the R strain of bacteria into the S strain. This molecule is DNA. He discovered that DNA was the material which genes and chromosomes are made. -
Erwin Chargaff
He 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 that the amount of adenine nearly equals the amount of thymine. He wrote this rule as C=G and T=A. -
Rosalind Franklin
She used a technique called X-ray diffraction that involved aiming X rays at the DNA molecule. Then she took the famous Photo 51. The contributed to the understanding of the molecular structure of DNA. -
Maurice Wilkins
He worked with a techique call X-ray deffraction, which involved aiming X rays at the DNA molecule. Franklin worked with him and took Photo 51. In 1953, Franklin and Wilkens provided evidence to support the structure proposed by Watson and Crick. -
Hershey and Chase
They used a method called radioactive labeling to trace the fate of the DNA and protein as the bacteriophages infected bacteria and reproduced. They concluded that that he DNA was injected in the cell and provided the genetic information needed to produce new viruses. This confirmed that DNA, not protein, was the genetic material. -
Linus Pauling
He proposed a triple-stranded helix structure for DNA. He had the phospate groups of each DNA standing facing into the helical, with the nitrogenous bases faces out. The three strands intertwined to make one helical DNA molecule. Pauling forgot that about the negative charges of the oxygen atom in each phosphate group. This would make it impossible for molecule to hold together, so his proposed structure of DNA was wrong. -
James Watson
Watson worked with Crick and they saw Franklin's X-ray defraction picture. Using Chargaff's and Franklin's data, they measured the width of the helix and the spacing of the bases. They built a model of the double helix DNA. -
Francis Crick
Crick worked with Watson and they saw Franklin's X-ray defraction picture. Using Chargaff's and Franklin's data, they measured the width of the helix and the spacing of the bases. They built a model of the double helix DNA.
