Dna 2

The determination of the DNA structure

By Maddy.Newton

  • Factors are noticed (Genes)

    Gregory Mendel publishes his work on the heredity of peas, in which he notes certain factors, later called genes, are passed from parent to offspring.

  • DNA was first isolated, analysed and recognized as a unique macromolecule.

    Nuclein was then changed to "nucleic acid" and then later, to its current name "deoxyribonucleic acid" (DNA) [Discovery of DNA Double Helix ](http://http://www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397)

  • Confirmation of Mendel's work

    Carl Correns, Eric Von Tschermark and Hugo DeVries confirm Mendel's work independantly

  • Important discoveries of genetics and chromosomal inheritance

    Thomas Hunt Morgan starts fly lab at Columbia university to study genetic variations. First fruit fly mutation discovered and then bred wirh a "wild type" resulting in offspring carrying that same mutation. From this, the physical basis of heredirt was established DNAi

  • Sex chromosomes determined

    XX- female
    XY- male
    independantly described by Nettie Stevens and Edmund Wilson

  • Genes are on chromosomes

    Thomas Hunt Morgan demonstrates that genes are situated linearly along chromosomes

  • First X-ray diffraction images taken

    By WIlliam Astbury

  • Linus Pauling discovers aplha helix shaped proteins ( shaped like a spring coil)

  • There is an 'A' for every 'T' and 'G' for every 'C'

    Erwin Chargaff reveals that there are equal amounts of nucleotides; Adenine (A), Thymine (T),Guanine (G) and Cytosine (C)

  • Wilkins and Gosling produce pictures of X-ray diffraction

  • X ray diffraction photos produced

    Rosalind Franklin produces X-rays of DNA. Watson and Crick correctly interpret, allowing he reconstruction of the 3-dimensional structure of the DNA molecule to show that DNA is a helical structure. History of Molecular Biology

  • Linus proposes triple stranded helix structure for DNA

    However, Linus forgot that the negative charge of the oxygen atom in each phosphate group - causing repelling charges, and thus making it impossible for the molecule to hold together.

  • Watson and Crrick publish first accurate model of the DNA molecule

    X-ray crystallography demonstrated that alternating deoxyribose and phosphate molecules form the twisted uprights of the DNA "ladder". The rungs of the ladder are formed by complementary pairs of nitrogen bases — A always with T and G always with C.

  • Central Dogma is first articulated by Crick - proteins cannot be used to create DNA

  • Nobel Prize awarded jointly to Watson, Crick and Wilkins

    For their work in discovering the structure of DNA. Rosalind Franklin was not given recognition for the award as the rules do not permit it to be given post-mortem Kinnear, J. F. & Martin, M. HSC course Biology 2, John wiley & sons Australia, 2001