The following are the main discoveries from the year 1860 to 2000:

1. 1865: Gregor Mendel shows that the characteristics of pea plants are passed along in a predictable way. His discovery begins the science of genetics.
2. 1903: Walter Sutton shows that chromosomes carry the cell’s units of inheritance.
3. 1911: Thomas Hunt Morgan demonstrates that genes are arranged in linear fashion on the chromosomes of the fruit fly.
4. 1928: Frederick Griffith discovers that bacteria contain a molecule that can transfer genetic information from cell to cell.
5. 1944: Oswald Avery, Colin Macleod, and Maclyn McCarty show the substance that Griffith discovered is DNA.
6. 1950: Erwin Chargaff analyzes the base composition of DNA in cells. He discovers that the amounts of adenine and thymine are almost always equal, as are the amounts of guanine and cytosine.
7. 1952: Alfred Hershey and Martha Chase confirm that the genetic material of viruses is DNA and not protein. Rosalind Franklin records a critical X-ray diffraction pattern, demonstrating that DNA is in the form of a helix.
8. 1953: James Watson and Francis Crick publishes their model of the DNA double helix. THe model was made possible by Franklin's work.
9. 2000: Craig Venter and Francis Collins announce the draft DNA sequence of the human genome at a White House ceremony in Washington, D.C. The final version is published in 2003.