Discovery of DNA

  • Work with heredity and genes

    Gregor Mendel publishes work on hereditary traits in peas. He notes that certain traits are passed from parent to offspring. Later these factors are called genes.
  • Johannes Friedrich Miescher

    Miescher isolated an unknown chemical from the nuclei of dead white blood cells and identified a chemically different substance and named it nuclein because it was found in the cell nucleus.
  • Acid, not protein, in a cell nuclei

    Friedrich Miescher describes an acidic substance in a cell's nuclei. This substance, first called nuclein, is now identified as DNA.
  • Phoebus Levene

    Levene thought that the DNA molecule was too simple to store the genetic code.
  • Linear genes discovered in chromosomes

    Thomas Hunt Morgan conducts experiments where he demonstrates that genes are located linearly along chromosomes.
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    X-ray crystallography

    British physicists Sir William Henry Bragg ( 1862-1942) and his son Sir Willam Lawrence Bragg (1890-1971) developed a new science of X-ray crystallography.
  • Genetic factor in bacteria transferred

    Frederick Griffith, in an experiment with mice, transfers the fatal component of a bacteria causing pneumonia to a benign strain of bacteria, which then causes fatal pneumonia in the mice. He then determined that there must be a genetic factor that can transform the bacteria.
  • Components of DNA discovered

    Phoebus Levene discovers deoxyribose sugar in nucleic acids. Later on, demonstrates that DNA is made up of nucleotides, which are composed of a deoxyribose sugar, a phosphate group, and a base.
  • Oswald Avery

    Proved Levenes to be wrong, DNA does hold the genetic code.
  • First pictures of DNA taken

    William Astbury takes X-ray diffraction pictures of DNA
  • Erwin Chargaff

    He made 3 discoveries.
    1) Nucleotides are not arranged in the same order in all species.
    2) In all species, the amounts of adenine and thymine are always similar to the amounts of guanine and cytosine. Chargaff's rule.
    3) The amount of adenine + guanine = thymine + cytosine.
  • More proof for DNA in genes over proteins

    Oswald Avery, Colin MacLeod, and Maclyn McCarty demonstrate that it is not protein but DNA that is the factor that Frederick Griffith identified.
  • Base pairs discovered

    Erwin Chargaff demonstrates that the bases of DNA are equal = there is an A for every T and a C for every G.
  • DNA crystals photographed

    Maurice Wilkins and Rosalind Franklin image DNA crystals via X-ray. These images are the basis for the conclusions of Watson and Crick.
  • Rosalind Franklin

    She discovered the density of DNA and, more importantly, established that the molecule existed in a helical conformation. Her work to make clearer X-ray patterns of DNA molecules laid the foundation for James Watson and Francis Crick's suggestion that DNA is a double-helix polymer.
  • Watson-Crick model

    James Watson and Francis Crick used information from Franklin's research and combined it with their findings and later that year they publish their research with diagrams of the double helix structure of DNA.
  • Watson and Crick describe double-helix DNA

    James Watson and Francis Crick publish their description of DNA. They describe it as a double-helix -two spirals held together by complementary base pairs.
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    Advances in genetics

    various discoveries of individual genes for cystic fibrosis, Huntington's disease, etc. Also, genetically engineered food, and animal cloning.
  • Nobel prizes

    Watson, Crick, and Wilkins jointly received for their work.
    Roseland Franklin did not receive a Noble prize as it can not be awarded after death.
  • The Double Helix

    Roseland Frankline was acknowledged when Watson wrote his book 'The Double Helix'.
  • Haemophilus Influenzae is the first bacterium genome sequenced

    the new strategy of "shotgun" sequencing, J. Craig Venter and colleagues published the first completely sequenced genome of a self-replicating, free-living organism - Haemophilus Influenzae. the bacterium that can cause meningitis and ear and respiratory infections in children. Prior to this breakthrough, scientists had only managed to sequence the genome of a few viruses, which are around ten times shorter than that of H.flu.
  • Dolly the sheep is cloned

    Dolly was the first mammal to be cloned from an adult cell. Animals such as cows had previously been cloned from embryo cells, Dolly demonstrated that even when DNA had specialized, it could still be used to create an entire organism.
  • First human chromosome is decoded

    In 1999, a team of researchers unraveled for the first time the full genetic code of a human chromosome. The chromosome in question was chromosome 22, which contained 33.5 million "letters," or chemical components.
    At the time, the sequence was the longest continuous stretch of DNA ever deciphered and assembled. However, it was only the first deciphered chapter of human genetic - the rest was still to come.
  • Human genome project

    Announcement of a draft of the human genome by a joint venture of the public and a private company called Celera.
  • Genetic code of the fruit fly is decoded

    In March 2000, scientists decoded the genetic makeup of the fruit fly. This effort had major implications for the sequencing of the human genome, as fly cell biology and development have much in common with mammals.
    During the research, the scientists discovered that every fruit fly cell contains 13,601 genes, making it by far the most complex organism decoded at the time. However, by contrast, human cells contain 70,000 genes.
  • Mouse is the first mammal to have its genome decoded

    Scientists decoded the genome of the first mammal – the mouse. The achievement allowed them to compare, for the first time, the human genome with that of another mammal. Amazingly, it emerged that 90% of the mouse's genome could be aligned with the corresponding regions on the human genome. Both the mouse and human genome also contained around 30,000 protein-coding genes. These discoveries highlighted for the first time just how closely mammalian species were genetically related.
  • Human genome complete

    Final completion of the human genome sequence announced.
  • DNA Worldwide and Eurofins Forensic discover identical twins have differences in their genetic makeup

    DNA Worldwide and their laboratory partners Eurofins Forensic were the first in the world to prove that twins have differences in their genetic make-up.
  • Further Breakthroughs

    Researchers successfully created an organism with an expanded artificial genetic code. Organisms that can produce medicines or industrial products organically were made. A study shows that more than 100 genes play a role in the development of schizophrenia. Researchers in Sweden found that changes in the expression of genes involved in inflammation, fat, and glucose metabolism could be behind the development of Type 2 Diabetes.