Scientists of DNA

By elizabeth.colwell201

  • Miescher

    Miescher
    -discovery made in approximately 1868
    -discovered that the substance found leukocyte cells was not a protein & derived from the nucleus . He called this substance nuclein & believed it might be the basis of heredity
    -discovery was made by isolating & chemically characterizing DNA from nuclei of leukocytes found in pus from bandages
    -before Miescher made his discovery and proved everyone wrong, it was believed that cells were largely made of proteins

  • Chargaff

    Chargaff
    -discovery approximately made in 1949
    -discovered that the relative amounts of A and T, and of G and C, are almost always equal. This became known as "Chargaff's Rule".
    -discovery was made by analyzing the base composition of DNA

    -discovery contributed to the understanding of DNA by allowing people to see that if two pyrimidines(T and C) or purines(A and G) were put together, the molecule would be too big

  • Franklin

    Franklin
    -discovered in approximately 1952
    -discovered that the X-ray patterns show the strands of DNA are twisted around each other like the coils of a spring(aka helix) and the angle of the X suggests that there are two strands of the structure.
    -Franklin used a technique called X-ray diffraction to make her discovery.
    - Her contribution showed the shape of the DNA molecule also know as a helix, but many thought it was discovered by Watson and Crick because they were first to publish her findings.

  • Hershey and Chase

    Hershey and Chase
    -discovery made in approximately 1952
    -confirmed that the genetic material of viruses is DNA, not protein
    -made their discovery by studying a bacteriophage that was composed of a DNA core and a protein coat
    -Hershey and Chase wanted to support or disprove Avery's findings that genes were made of DNA because it had not been proven

  • Watson and Crick

    Watson and Crick
    -discovery made in approximately 1953.
    -found that each strand of DNA molecule was a template for the other. In cell division, the two strands separate & on each strand a new side is built like the original. also found that hydrogen bonds could form between certain nitrogenous bases
    -discovery was made by Watson stealing Fraklin's results & sharing it with Crick.
    -Their discovery added on to Franklin's discovery & they also found that hydrogen bonds hold certain nitrogenous bases together

  • Meselson and Stahl

    Meselson and Stahl
    -discovery made in approximately 1957
    -discovered the semi-conservative replication of DNA
    -made their discovery by inventing a new technique called density gradient centrifugation, which uses centrifugal force to separate molecules based on their densities
    -Meselson and Stahl discovered that DNA replication to RNA was semiconservative, which people did not know until then