A transforming factor can change phenotype
Frederick Griffith (1928)
Genes are on chromosomes
T.H. Morgan (1908)
Transforming factor is DNA
Avery, McCarty, MacLeod (1944)
A/T C/G
Erwin Chargaff (1947)
Confirmation that DNA is genetic material
Hershey & Chase (1952)
Determined double helix structure of DNA
Watson and Crick (1953)