-
Friedrich Miescher
Isolated nucleic acids from the nuclei of white blood cells, which he collected from bandages from a clinic. he was the first person to raise the idea that the nucleic acid could be involved in heredity. -
Frederick Griffith
Griffith experimented using two strands of pneumococus bacteria injected into mice. With the rough strand the mouse would live, the smooth strand would kill the mouse. He then killed the smooth bacteria with heat and when mixed with the rough strand, injected a mouse. The mouse died. Griffith concluded that the rough strain had been "transformed" into the deadly strain. signifigance is he discoverd transforation but the cause was still unknown. -
Avery, MacLeod, and McCarty
They purified from bacteria the "transforming factor" which was not a protein but DNA. They performed tests in a test tube and not mice, and got the same results as Griffith. Conclusion: DNA is responsible for reproduction. -
Franklin and Wilkins
They used X-Ray crystallagraphy to determine molecular structure. These x-Ray photographs showed DNA to have a double helix structure. They provided the information for Watson and Crick to make a model of DNA -
Erwin Chargaff
He isolated Adenosine, Guanine, Cytosine, and Thymine from different organisms and formulated two rules. 1. All DNA shares certain properties and that the amount of A was equal to the amount of T and the amount of C was equal to the amount of G 2. Nucleotides do not repeat in the same order but vary for different species -
Hershey and Chase
Conducted experiments using phages, viruses that infect bacteria. When the DNA of phages was radioactively labled and the phage infected bacteria with genetic material, radioactivity entered the cell. When the protein coats of phages were radioactively labeled and they infected the bacteria, no radioactivity entered the cell. t
This confirmed that DNA is the genetic material. -
Watson and Crick
Built a model of DNA. Concluded that DNA structure is a 3 dimensional, double stranded helix with bases connected by H bonds, A paired with T and C paired with G. They concluded that DNA replicated by separating into 2 strands andthese strands paired with complimentary bases to make new a new helix.
