By 1944, researchers by the names of Oswald Avery, Colin MacLeod, and Maclyn McCarty wanted to continue the work of Griffith and started by growing bacteria in liquid cultures
The researchers had to prepare 3 identical extracts of the heat killed S-strain bacteria. This was accomplished by isolating the bacteria, disrupting the cell membranes and collecting the cell contents.
RNA destroying enzyme mixture
Protein destroying enzyme mixture
They added a different enzyme to each extract. One to destroy protein, one to destroy RNA, and one to destroy DNA. The goal was to find out which of the 3 was responsible for and caused the transformations.
Responsible for passing down genetic information
Each enzyme-treated extract was mixed with live R-strain cells. All three mixtures were investigated to find out which enzyme addition revealed the answer to these transformations.
The mixture that left the R-strain as non-pathogenic was the one containing DNA-destroying enzymes. This means the DNA is responsible for the transformation and for passing down genetic information in general.
DNA destroying enzyme mixture
The researchers were thrilled with their discovery that DNA was structure that contained and passed down genetic information. This would be a guide for scientists to further their study on DNA.