- In 1944, Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that nucleic acids isolated from the heat-killed deadly (S) strain of a bacteriophage were responsible for transforming the harmless (R) strain into the deadly form. Their work demonstrated that DNA, not protein, is the genetic material. - In 1952, Alfred Hershey and Martha Chase conducted a series of experiments involving the reproduction of bacteriophages, viruses that infect bacteria. The bacteriophages land on bacteria, invade, and reproduce inside the bacterial cells. - Hershey and Chase capitalized on the fact that viruses are simple structures consisting of two basic molecules, a protein coat and DNA. One of the two molecules had to be the genetic material, capable of using bacteria to producing more viruses. - The sulfur in bacteriophage protein coats was labeled with 35S and the phosphorus in the DNA was labeled with 32P. - During viral reproduction, the protein coats remained on the outside of the bacterial cells and could be separated from the cells without affecting viral replication. New viruses produced inside bacterial cells contained radioactive DNA. - The experiments demonstrated that DNA is the genetic material.

Where was the radioactive sulfur-35 at the end of Hershey and Chase’s experiments?

- in the protein coat of the parent phages on the outside of the E. coli cells

In attempting to determine the transforming chemical, Avery and his colleagues isolated chemicals from heat-killed pathogenic bacteria and tried to transform live nonpathogenic bacteria. Their experimental results indicated that

- DNA was the transforming chemical

The basis behind the experiments of Avery and his coworkers came as a result of which of the followng experimental results?

- Griffith's experiments on smooth and rough strains of Pneumococcus

Bacteriophages have a __________ and a __________.

- DNA or RNA core; protein coat

6.1.4 Avery, MacLeod and McCarty/Hershey and Chase: DNA Wins! Flashcards by Irina Soloshenko

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6.1.4 Avery, MacLeod and McCarty/Hershey and Chase: DNA Wins! Flashcards

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