DNA Timeline
Timeline Description: DNA, the molecule carrying the genetic instructions of life, was arguably one of the most important discoveries of the last century. DNA is used in the development of all forms of known life, is composed of 4 nucleotides, and has the form of a double helix. This is a timeline of the discovery and development of DNA.

Date Event
1866 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.
1869 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.
1911 Linear genes discovered in chromosomes

Thomas Hunt Morgan conducts experiments where he demonstrates that genes are located linearly along chromosomes.
1928 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 cause a fatal pneumonia in the mice. He then determined that there must be a genetic factor that can transform the bacteria.
1929 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.
1943 First pictures of DNA taken

William Astbury takes X-ray diffraction pictures of DNA
1944 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.
1950 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.
1952 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.
1953 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.
1953 Advances in genetics (1953-1996)

various discoveries of individual genes for cystic fibrosis, Huntington's disease, etc. Also, genetically engineered food, and animal cloning.
2000 Human genome project

Announcement of a draft of the human genome by a joint venture of the public and a private company called Celera.
2003 Human genome complete

Final completion of the human genome sequence announced.






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