History of DNA. Who Discovred DNA??

By rahea10

  • Nucleotides

    Nucleotides
    P.A. Levene determined the basic structure of nucleotides that make up DNA. Nucleotides are the subunits of nucleic acids and conist of a five-carbon sugar, a phosphate group, and a nitrogenous base. The two nucleic acids found in living cells are DNA and RNA.

  • Griffith

    Griffith
    Griffith performed the first major experiment that led to the discovery of DNA. He studied two strains of bacteria Strptococcus pnneumoniae, which causes pneumonia. He found that one strain could be transformed into the other form. One of the strains that he studied had a sugar coat and the other did not. The sugar coated strain caused pneumonia and is called the smooth strain. The noncoated strain that does not cause pneumonia is called the rough.

  • Avery

    Avery
    Oswald Avery and his collegues identiied the molecule that transformed the R strain of bacteria into the S strain. Avery isolated different molecules from the killed S cells, such as DNA, protein, and lipids. Then he expose the the live R cells to the macromolecules separately. When the R cells were exposed to the S Strain DNA, they were tansformed into S cells. He concluded that when the S cells in Griffith's experiments were killed, DNA was released.

  • Maurice Wilkins

    Maurice Wilkins
    He took the first ever image of the DNA molecule.Wilkin's doctoral thesis dealt with the study of the thermal stability of trapped electrons on phosphores, and on the theory of phosphorescene in terms of electrons.. He applied his research during WW2, to improving cathose-ray tube screens for radar.

  • Chargaff

    Chargaff
    Erwin Chargaff analyzed the amount of adenine, guanine, thymine, and cytosine in the DNA of vaious species. He found that the amount of guanine nearly equals the amount of cytosine, and the amount of adenine nearly equals the amount of thymine within a species. This finding is known as Chargaff's rule: C=G and T=A.

  • Watson and Crick

    Watson and Crick
    Using Chargaff's data and Franklin's data, Watson and Crick measured the width of the helix and the spacing of the bases. They build a model of the double helix that conformed to the others' research.
    Some important features of their proposed molecule included the following:
    1.) 2 outside strands consist of alternating deoxyribose phosphate.
    2)Cytosine&guanine bases pair to each other by 3 hydrogen bonds.
    3) Thymine&adenine bases pair to each other by 2 hydrogen bonds.

  • Linus Pauling

    Linus Pauling
    Linus worked out the structure of proteins. This included the structure of the alphha helix chain. His findings were the key to understanding biology at the molecular level and a catalyst for researchers wanting to find out the function of proteins in the body.

  • Franklin

    Franklin
    A technique that involved aiming X rays at the DNA molecule, called X-ray diffracition. Franklin indicated that DNA was a double helix, or twisted ladder shape, formed by 2 strands of nucleotides twisted around eachother. DNA is the genetic material of all organisms, composed of two compementary, precisly paired strands of nucleotides wound in a double helix.

  • Hershey and Chase

    Hershey and Chase
    They published results of experiments that provided definitive evidence that DNA is the transforming factor. These experiments involved a type of virus that attacks bacteria. TWo components made the experiment ideal for confirming that DNA is the genetic material.They labeled both parts of the virus to determine which part was injected into the bacteria and which part was the genetic material.