DNA by Rebecca Day

By Rebecca.day

  • Miescher

    Miescher
    -was able to isolate nuclein from the nucleus laying the ground work for the molecular discoveries later on.
    -discovered this by studying white blood cells in pus but later disproved he could do the same to salmon sperm
    -this helped our understanding of DNA later on because these were alter to be discovered as the nucleic acids in DNA

  • Chargaff

    Chargaff
    -He discovered that the percentages of adenine and thymine bases are almost equal in any sample of DNA and that the same thing is true for the other two bases guanine and cytosine.
    -he discovered this by finding the nitrogenous bases in many samples of a species to be equal so he looked father in to other species.
    -this helps with the discovery of DNA because we know that all species have the same properties that make up DNA.

  • Hershey & Chase

    Hershey & Chase
    -Hershey and Chase found that DNA is the genetic material that infects bacteria.
    -they found this by a serious of experiments of adding bacteria and phage which is a protein to a radioactive element. But the bacteria later on did not show the radioactive element later on while the phage did.
    -this helped the discovery of DNA because we now know that it fights off bad things in our bodies

  • Franklin

    Franklin
    -showed X-ray pattern that shows two strands twisted around each other, found a clue to suggest the nitrogenous bases are near the middle
    -she used the technique called X-ray diffraction=she purified a large amount of DNA, stretched the fibers in a thin glass tube so the strands were parallel, she then aimed a powerful X-ray beam at the DNA samples and recorded the scattering patterns of the X-rays on film.
    -helped Watson and Crick with the shape of a chromosome and why it was shaped that way

  • Watson & Crick

    Watson & Crick
    -discovered that DNA was structured in a double-helix model with hydrogen bonds holding nitrogenous bases together.
    also that the bases A and T go together and the bases C and G go together.
    -The clues in franklins X-ray pattern enabled Watson and Crick to build a model of DNA that explained the specific structure and properties of the DNA.
    -what gave credit to their discovery was franklins paper that was published that described her x-ray work

  • Meselson & Stahl

    Meselson & Stahl
    -proved that the semiconservative model of DNA replication was correct.
    -found this by labeling DNA bacteria across generations using isotopes of nitrogen.
    -this improved the knowledge of DNA because of that we knew that DNA splits and when it does it contains the same genetic material