Hershey and Chase Experiment: DNA is the Molecule of Heredity

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The classic Hershey and Chase Experiment proved conclusively that DNA was the molecule of heredity in 1952.
Dr. Alfred Hershey and Dr. Martha Chase’s now famous experiment was actually the third major investigation into what genes are made of. They learned from the previous work of Frederick Griffith in 1928 and Oswald Avery, Colin MacLeod and Maclyn McCarty in 1944.
Griffith's Experiment Video: • Griffith's Experiment:...
Avery Experiment Video: • Avery Experiment: DNA ...
Avery Experiment Handout: etsy.me/3DvLDv6
Hershey and Chase harnessed the viral life cycle to prove which of the two contenders was actually responsible for inheritance; proteins or nucleic acids. Hershey and Chase used two groups of bacteriophages, and made a single component radioactive in each one to keep track of what it was doing. In one group, they tested the viral protein coat on the outside, and in the other group they tested the nucleic acids on the inside of the virus.
The experiment consisted of three major steps; infection, blending, and centrifugation. In the infection step, Hershey and Chase then allowed each type of bacteriophage to infect a host cell to see whether the radioactive proteins or the radioactive nucleic acids would make radioactive bacteriophages. Next, in the blending step, they used a high speed blender to jiggle the e coli cells enough to shake off the empty protein shell from the outside. (This is why this experiment is sometimes affectionately referred to as the “Blender Experiment”). This created a mixture of liquid, phage parts and bacteria called a “suspension”. Finally, in the centrifugation, they spun this mixture in a centrifuge so that the heavier bacteria condensed and formed a pellet at the bottom of the test tube. Since the virus particles were much smaller and lighter, they remained suspended in the liquid or the “supernatant”.
Hershey and Chase found that the supernatant was more radioactive in the protein group, and the pellet was more radioactive in the nucleic acid group, indicating that the viral DNA had entered the cell. This provided very compelling evidence that nucleic acids, not proteins, were the molecule of inheritance.
0:00-0:11 Introduction
0:11-0:34 Biomolecules
0:34-1:28 Griffith's Transforming Principle Experiment
1:29-2:11 Avery Experiment Claims DNA is the Transforming Principle
2:11-3:54 Hershey and Chase Harness T4 Bacteriophages
3:55-4:38 Key Elements of Proteins and Nucleic Acids
4:39-5:28 Hershey and Chase Experiment Design
5:29-6:26 Hershey and Chase Experiment Results
6:27-6:42 Response to the Hershey and Chase Experiment
6:43-7:00 Nobel Prize committee snubs Dr. Martha Chase
7:00-7:14 Conclusion
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[BOGObiology]. (2021, November 17). Hershey and Chase Experiment: DNA is the Molecule of Heredity. [Video File]. Retrieved from • Hershey and Chase Expe...
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