DNA an Genetics History Timeline

Gregor Mendel published work on hereditary traits in peas. He notes that certain traits are passed from parent to offspring. Later these factors were called genes.

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

Walther Flemming discovers a substance he calls chromatin. He notices that, during cell division, this substance separates into threadlike strings, which become known as chromosomes.

Mendel’s research is rediscovered by botanists Theodor Boveri and Walter Sutton in 1900. Then they independently notice the link between Mendel’s “units of inheritance” and chromosomes. They conclude that hereditary information is contained within chromosomes.

Thomas Hunt Morgan is the first to discover a sex-linked trait while studying the fruit fly Drosophila. The trait for eye color, on the X chromosome, is also the first gene to be traced to a specific chromosome.

Oswald Avery, Colin MacLeod, and Maclyn McCarty revisit work from the 1920s and prove that, in bacteria, DNA is the hereditary material and not protein as was previously suspected in 1951.

in 1950, Erwin Chargaff discovers regularity in proportions of DNA bases for different species. In all organisms he studies, the amount of adenine (A) approximately equals that of thymine (T), and guanine (G) equals cytosine (C).

James Watson and Francis Crick, with contributions from Rosalind Franklin and Maurice Wilkins, discover the double helix structure of DNA.

The international Human Genome Project begins, with the goal of sequencing the entire human genetic code. Gene therapy is used successfully for the first time, to treat a four-year-old girl with the rare hereditary immune disorder adenosine deaminase deficiency.

Human Genome Project is completed and confirms humans have approximately 20,000–25,000 genes. The human genome is sequenced to 99.99 percent accuracy, 2 years ahead of schedule.