didn't know what carried genes, but knew the substance needed to:
1. Contain inforrmation
2. Be easy to copy
3. Be variable, to account for diversity
DNA or protein?
3. So, which is the genetic material?
Griffith Experiment (1928)
Transformation of one strain of bacteria by another. 2 strains:
Heat-killed S is harmless, but when added to R, the strain becomes deadly
Hershey and Chase (1952)
Labeled viruses with radioactive material. When they labeled sulfur, the
labeled protein did not get transferred to the cell. When they labeled
phosphorus, only in DNA, the labeled material was transferred, proving that
DNA carried genetic material.
Watson and Crick (1953)