History of DNA Timeline

By agm0383

  • Oswald Avery

    Oswald Avery published a clinical study about the tuberculosis bacterium in 1913.The work he did leading up to his study being published included using different immunological and chemical methods on different strains of bacteria. Avery also indentified polysaccharide and he showed that it could stimulate production of antibodies in the immune system. He worked with Maclyn McCarty and Colin MacLeod to discover that DNA controlled the transfer.

  • Frederick Griffith

    During the 1920s Fredrick Griffith showed that a substance could be transferred to harmless bacteria and then make them deadly.He found this out by studying 2 strands of bacterium called R and S. He then injected the strands into mice. At first the S killed that mice, but the R did not. He injected the mice again with S, but they did not die. He then injected the mice with dead S and live R, and the mice died.His dicovery lead Avery to question his results.

  • Erwin Chargaff

    Erwin Chargaff isolated DNA in different organisms and measured the level of each of the four bases. He found that the concentration of bases in one organism differed from the concentration in another organism. However with the concentration of adenine and thymine are always about the same. This is also true with guanine and cytosine. This is known as Chargaff's Rules.

  • Alfred Hershey and Martha Chase

    The idea that DNA was a genetic material wasn't widely excepted, so in the 1950s Hershey and Chase did more research.They used different radioactive elements to label DNA and proteins in different viruses inside bacteria. They were then able to identify the molecule of DNA, which confirmed DNA as a genetic material.

  • Rosalind Franklin

    Rosalind Franklin produced x-ray crystallography pictures of BDNA, that were used by scientists later on to make important discoveries. To do so she used 1 hydrated fiber and one less hydrated fiber of DNA She was then able to deduct that the phosphate groups had to be on the outside of a helical structure. She presented her information and Watson heard what she had found. Watson took her pictures to Crick and together they published a paper using Franklin's infomation.

  • Watson and Crick

    In 1953 Watson and Crick published a paper about the double helix using information that Rosalind Franklin and other scientists had discovered. The scientists used x rays to learn more about DNA's structure. They are known for building the first accurate model of DNA.