Martha Chase and Alfred Hershey conducted an experiment separately labeling the DNA and proteins of the T2 bacteriophage to determine which component was the genetic material responsible for the production of new phage particles.
By the time
Hershey and Chase published their experiment in the early 1950s, microbiologists and other scientists had been researching heredity for over 80 years. Building on one another’s research during that time culminated in the general agreement that DNA was the genetic material responsible for heredity (
[link] ). This knowledge set the stage for the age of molecular biology to come and the significant advancements in biotechnology and systems biology that we are experiencing today.
To learn more about the experiments involved in the history of genetics and the discovery of DNA as the genetic material of cells, visit this
website from the DNA Learning Center.
How did Hershey and Chase use microbes to prove that DNA is genetic material?
A timeline of key events leading up to the identification of DNA as the molecule responsible for heredity
Key concepts and summary
DNA was discovered and characterized long before its role in heredity was understood. Microbiologists played significant roles in demonstrating that DNA is the hereditary information found within cells.
In the 1850s and 1860s, Gregor Mendel experimented with true-breeding garden peas to demonstrate the
heritability of specific observable traits.
In 1869, Friedrich Miescher isolated and purified a compound rich in phosphorus from the nuclei of white blood cells; he named the compound nuclein. Miescher’s student Richard Altmann discovered its acidic nature, renaming it
nucleic acid . Albrecht Kossell characterized the
nucleotide bases found within nucleic acids.
Although Walter Sutton and Theodor Boveri proposed the
Chromosomal Theory of Inheritance in 1902, it was not scientifically demonstrated until the 1915 publication of the work of Thomas Hunt Morgan and his colleagues.
Using
Acetabularia, a large algal cell, as his model system, Joachim Hämmerling demonstrated in the 1930s and 1940s that the nucleus was the location of hereditary information in these cells.
In the 1940s, George Beadle and Edward Tatum used the mold
Neurospora crassa to show that each protein’s production was under the control of a single gene, demonstrating the
“one gene–one enzyme” hypothesis .
In 1928, Frederick Griffith showed that dead encapsulated bacteria could pass genetic information to live nonencapsulated bacteria and transform them into harmful strains. In 1944, Oswald Avery, Colin McLeod, and Maclyn McCarty identified the compound as DNA.
The nature of DNA as the molecule that stores genetic information was unequivocally demonstrated in the experiment of Alfred Hershey and Martha Chase published in 1952. Labeled DNA from bacterial viruses entered and infected bacterial cells, giving rise to more viral particles. The labeled protein coats did not participate in the transmission of genetic information.
Fill in the blank
The element ____________ is unique to nucleic acids compared with other macromolecules.
Bacteriophages inject their genetic material into host cells, whereas animal viruses enter host cells completely. Why was it important to use a bacteriophage in the Hershey–Chase experiment rather than an animal virus?
