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According to my bio book, I think it's Alfred Hershey and Martha Chase, in the HERSHEY-CHASE experiment.
Hershey and Chase observed that DNA is the identity of the hereditary material in phage T2. Hershey and Chase used radioactive labels to mark the protein of the bacteriaphage in one experiment and the DNA in another.
Hershey and Chase observed that DNA is the identity of the hereditary material in phage T2. Hershey and Chase used radioactive labels to mark the protein of the bacteriaphage in one experiment and the DNA in another.
Their genetic material
Their genetic material
The idea of their experiment was to determine what kind of macromolecule was the genetic material, DNA or proteins. Bacteriophages, viruses that infect bacteria, were known to carry all of the information needed to make themselves, but using the genetic machinery of their hosts. Based on this, they were used as a simple system that should be governed by the same principals as the genetic information of the bacteria itself. At the time it was known that nearly all phosphorus in macromolecules is found in nucleic acid, and nearly all sulfur is found in proteins (methionine and cycteine). So if you grow cells in radioactive isotopes of phosphorus, the nucleic acids (e.g. DNA) become radioactive, and if you grow cells in radioactive sulfur, proteins become radioactive. Sorry, there's more. Folks studying infection of bacteria by phage found that most of the virus was a "package" that never entered the cell. So if they mixed phage with bacteria and waited 15 minutes and then put the mix in a blender for a few seconds, the packages that had been attached to the outside of the bacteria get ripped off and can be searated from the bacteria. While the packages are no longer attached to the bacteria, the bacteria are already infected, so the virus genes must already be inside. Now the experiment: Hershey and Chase infected bacteria with phage with racdioactive proteins (sulfur) or in a separate experiment radioactive DNA (phosphorus). The bacteria was mixed with virus for 15 minutes, then whoosh, frappe! They then separated the bacteria from the viruses that had not infected bacteria and empty packages, and asked what kind of radioactive macromoleules were able to get inside the bacteria following the short incubation. In the sulfur experiment , the bacteria were NOT radioactive so proteins appeared to not enter the bacteria during this short time frame. In the phosphorus experiment, the bacteria became radioactive after a short incubation, meaning the DNA of the phage had entered the bacteria in the same time frame as the genetic material. This was consistent with DNA being the genetic material of bacteriophage.
According to my bio book, I think it's Alfred Hershey and Martha Chase, in the HERSHEY-CHASE experiment.
The genetic mateial is made of DNA and not of proteins
it was phage
The genetic mateial is made of DNA and not of proteins
In their experiments, Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. Although the results were not conclusive, and Hershey and Chase were cautious in their interpretation, previous, contemporaneous and subsequent discoveries all served to prove that DNA is the hereditary material.
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