Studying viruses can be important because they are often disease causing pathoge
ID: 80760 • Letter: S
Question
Studying viruses can be important because they are often disease causing pathogens. However, because of how easy they are to control and manipulate in the laboratory, viruses can be good tools to study basic, fundamental principles of cell and molecular biology. Explain one example of how viruses were used to make a critical molecular biology/ genetics discovery Make sure to address 1) how was the experiment done, 2) what was concluded by the scientists, 3) what were the broad implications of the study?)Explanation / Answer
Answer: Viruses (bacteriophage) were used to conduct a series of experiments that helped to confirm that DNA is the genetic material. These experiments are known as Hershey Chase experiments. These experiments were performed in 1952 by Alfred Hershey and Martha Chase. At that time the usual assumption for the hereditary genetic material was proteins because of their complex structure rather than DNA owing to its simpler structure. Hershey and Chase throught their experiments demonstrated that when bacteriophage infects the bacteria, their DNA enters the host bacterial cell and not the viral protein.
1) How was the experiment done
Experiment was performed by using radiolabeled Sulfur and Phosphorus to label protein shell and DNA of the T2 phage separately. Radioactive sulfur-35 was used to label the protein content (sulfur is a constituent of amino acids) of the phage whereas radiolabeled Phosphorus-32 was used to label the phage DNA. These radioactive elements were added to the media in which the bacteria were growing and phages were introduced in the media and allowed to infect the bacteria. This resulted in the incorporation of radiolabeled sulfur and Phosphorus in the phage proteins and DNA respectively.
This labeled progeny was subsequently allowed to infect the unlabeled bacteria. Upon infecting the bacteria, only the labeled DNA (genetic material) entered the bacteria whereas the protein coat remained outside. The phage coat was separated from the bacteria by using a blender and performing centrifugation. When the bacteria were lysed and phage progeny were released - it was found that the phages that were labeled with P-32 initially were still labeled, however, the phages that were labeled with S-35 initially, didnot carry this label further in the progeny thereby confirming that DNA is the genetic material.
2) what was concluded by the scientists:
Based on the experimental findings, Hershey and Chase concluded that DNA is the genetic hereditary material and not protein.
3) What were the broad implications of the study?
Hershey Chase experiment stand out as an turning point in scientific history and had a substantial impact on the thinking and assumption of the scientific community.