Dna 6339076 lrg

HSW The story of the double helix

By tommasogianaroli
  • Period: to

    Period of Gregor Mendel's life

  • Introduced concept of individual inherited particles

    Gregor Mendel introduced these particles, later called GENES by the scientific community

  • Knowledge about DNA

    By this time the basic DNA structure was known, in addition they known that there are 4 different type of bases
  • Period: to

    Periond of Linus Pauling's life

    Nobel prize-winning, biochemist.
    He showed that polypeptide chains a often held in the shape of a alpha-helix by hydrogen bonds, which could be broken down with little heat.
    He suggested that there could be similar helical structure, in order to explain changes that happened in DNA heating
  • Period: to

    Periond of Erwin Chargaff's life

  • Period: to

    Period of Maurice Wilkins's life

    He worked with Rosalind Franklin on the X-RAY DIFFRACTION.
    It was very difficult to get pure crystals of DNA (it doesn't crystallise easily).
    Franklin developed methods of obtaining the highest quality x-ray DNA molecule pictures.
    Thanks to this discovery she could build up a two-stranded helical model structure of DNA.
  • Period: to

    Period of Rosalind Franklin's life

  • Period: to

    experiment: destroy different type of molecules

    Experiment carried out by: Oswald Avery, Colin Macleod, Maclyn McCarty
    They demonstrated that DNA was the inherited material, because after the DNA was destryed there was no transformation, not even proteins had effect on transofrmation.

  • Discovered tat proportion of cytosine and guanine were the same

    Discovered by Erwin Chargaff. He also found that the proportion of adenine was the same as of thymine, but No relationship between other combinations of bases.

  • Mauris Wilkins and Rosalind Franklin discovery

    Maurice Wilkins worked with Rosalind Franklin on the X-RAY DIFFRACTION.
    It was very difficult to get pure crystals of DNA (it doesn't crystallise easily).
    Franklin developed methods of obtaining the highest quality x-ray DNA molecule pictures.
    Thanks to this discovery she could build up a two-stranded helical model structure of DNA.
  • Period: to

    James Watson and Francis Crick built a DNA model that fitted with all the facts

    They built a double helix structure model, without carried out an experiment. To build this they accumulated lots of informations from different resources. The pattern from the x-ray crystallography supposed a helix measuring 3.4 nm (for every complete turn). In addition Watson noticed that thymine was paired with adenine and that cytosine was paired with guanine, H-bonds would hold them together. The 2 sets of base pairs have (roughly) the same size. 10 base pairs would make up 1 complete twist