Gregor Mendel observes and records his experiments with pea plants for hereditary factors.
Thomas Hunt Morgan experimented on fruit flies and observed them and he found out that certain traits are linked to certain sexes. He discovered sex linked traits.
While trying to find a vaccine to Streptococcus pneumonia he discovered that the heat killed virulent cells of this could transform the non-virulent cells into virulent cells so they would be dangerous. This is called transformation
Oswald Avery experimented on transformation and found out that DNA is the hereditary material that is passed between cells to cause transformation.
Rosalind Franklin took photos of DNA that were used to create the double helix structure for DNA
Martha Chase and Alfred Hershey experimented to figure out if it was DNA or Protein that viruses exchange to transform. They used forms if radioactive isotopes and a centrifuge to figure this out. They found out is was DNA.
James Watson and Frances Crick developed the structure of DNA using Rosalind Franklin's photos.
Scientists around the world launch the human Gnome project, who's goal is to map the entire human DNA structure.