Final answer:
DNA was identified as the genetic material responsible for the transformation of bacterial strains, a discovery credited to Oswald Avery and his colleagues. The Hershey-Chase experiment later confirmed DNA's role in heredity.
Step-by-step explanation:
The substance capable of genetically transforming other bacterial strains was determined to be DNA. This discovery was made by scientists Oswald Avery, Colin MacLeod, and Maclyn McCarty.
Their pivotal research in 1944 involved systematic elimination studies using enzymes that specifically degraded various components such as proteins, RNA, and DNA, within bacterial cells. They concluded that when DNA was degraded, the mixture lost its ability to transform bacteria, implicating DNA as the transforming principle.
Later, in 1952, the Hershey-Chase experiments provided further confirmation that DNA is the genetic material. They used radioactive labeling to demonstrate that DNA from bacteriophages entered bacterial cells and directed the creation of new virus particles, while the protein coats did not participate in the transmission of genetic information.