Final answer:
Martha Chase and Alfred Hershey are credited with the definitive demonstration that DNA is the genetic molecule, using experiments involving bacteriophages in 1952. This work built upon previous findings and led to our modern understanding of DNA and its role in heredity.
Step-by-step explanation:
The scientists who obtained definitive results demonstrating that DNA is the genetic molecule were Martha Chase and Alfred Hershey. Their 1952 experiments with bacteriophages provided the conclusive evidence that DNA carried genetic information, not proteins. This discovery was pivotal to our understanding of heredity and genetics, advancing the field of molecular biology.
While Griffith's experiments in the 1920s hinted at the presence of a transforming principle and Avery, MacLeod, and McCarty's work in the 1940s suggested DNA was this substance, it was the Hershey-Chase experiments that definitively confirmed DNA's role as the genetic molecule. They used a bacteriophage and demonstrated that only the DNA, not the protein component of the virus, was necessary to direct the production of new viruses within infected bacteria.
Watson and Crick are credited with describing the molecular structure of DNA, with valuable contributions from Rosalind Franklin's X-ray diffraction patterns elucidating the double helix structure. The collective work of these scientists has led to our current understanding of DNA and its function in genetics.