Whereas old dependency theory was Marxist in presentation, but nationalist in orientation, seeking to combine a theory of class struggle with a nationalist âthird worldistâ ideology, the new dependency theory is institutionalist in its analysis and political orientation.
Griffith concluded that the type II-R had been transformed into the lethal III-S strain by a transforming principle that was somehow part of the dead III-S strain bacteria. Today, we know that the transforming principle Griffith observed was the DNA of the III-s strain bacteria. While the bacteria had been killed, the DNA had survived the heating process and was taken up by the II-R strain bacteria. The III-S strain DNA contains the genes that form the protective polysaccharide capsule.
Experiments by Hershey and Chase in the 1950s using the bacteriophage T2 and E. coli cells demonstrated that DNA is the genetic material of the bacteriophage. Also, the experiments by Avery, Macleod, and McCarty demonstrated that the transforming material initially identified by Griffiths was DNA.very and his colleagues demonstrated that DNA is the transforming material by using enzymes that destroyed the different classes of biological molecules. Enzymes that destroyed proteins or nucleic acids had no effect on the activity of the transforming material.