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Experiment

Hershey-Chase Experiment

Life Sciences

Alfred Hershey and Martha Chase labeled the protein coat of a virus that infects bacteria with radioactive sulfur and its DNA core with radioactive phosphorus, let the viruses infect bacteria, then spun the mixture in a blender and a centrifuge to knock loose and separate whatever had stayed outside the bacterial cells from whatever had gone in. The phosphorus label, marking DNA, entered the bacteria and was passed on to new virus particles; the sulfur label, marking protein, stayed outside. Since a virus needs to inject only its genetic material to reprogram a cell, the result showed that DNA, not protein, is the molecule that carries genetic information, closing a debate that had run for decades. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/

Facts
YearSourced to the subject's own account
1952 1
MethodSourced to the subject's own account
Hershey and Chase labelled separate batches of bacteriophage with radioactive phosphorus-32 (marking DNA) or sulfur-35 (marking protein), infected bacteria with each batch, then used a kitchen blender to shear the phage coats off the cells before centrifuging to see which isotope had entered the bacteria. 1
Key FindingSourced to the subject's own account
The radioactive phosphorus (DNA) entered the bacterial cells and was passed to progeny phages, while the radioactive sulfur (protein) mostly stayed outside, demonstrating that DNA, not protein, is the hereditary material. 1
Connections

Conducted By

Source Alfred Hershey (Britannica)
Source Martha Chase (Britannica)

Uses

Sources
1. Hershey-Chase Experiment (Wikipedia)
Wikipedia
  • Procedure section
    Radioactive phosphorus-32 was used to label the DNA...Radioactive sulfur-35 was used to label the protein sections of the T2 phage, because sulfur is contained in protein but not DNA.
  • Results section
    Only 20% of the 32P remained outside the cell...All of the 35S in the protein coats remained outside the cell.
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