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What did Hershey and chase find through their experiment with virus -infected bacteria?
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∙ 8y ago
The genetic mateial is made of DNA and not of proteins
Kathryn Lebsack
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What did Hershey and Chase find through their experiments with virus-infected bacteria?
The genetic mateial is made of DNA and not of proteins
What did hershey and chase find through their experiment with virus-infected bacteria?
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.
What causes Rickettsialpox?
The specific bacteria responsible for rickettsialpox is called Rickettsia akari. A person contracts this bacteria through the bite of an infected mite.
What was the goal of the Hershey-Chase experiment?
- A series of experiments conducted in 1952 by Alfred Hershey and Martha Chase confirming that DNA was the genetic material in cells - The experiment was conducted using T2 phage; a virus that infects bacteria. They do so by attaching to the surface of a bacterium and injecting its genetic material into the bacteria. The structure had recently been elucidated by electron microscopy. - The 1st experiment- Phage DNA was labeled with radioactive 32P. Phosphorous is an important component of DNA which is not found in Amino Acids; protein building blocks. - The phages were allowed to infect E.coli bacteria and through a series of elegant experiments they were able to observe transfer of labeled phage DNA into the cytoplasm of the bacteria. - In the second experiment, they labeled phages with radioactive Sulfur 35 which is found in amino acids cysteine and Methionine. After infection of E.coli, they sheared off the phage protein shells from the infected cells using high speed blender and centrifugation to separate. - After centrifugation, the radioactive sulfur was found in the protein portion confirming the hypothesis that the genetic information transferred was DNA and not protein
What wander through the interstitial fluid eating whatever bacteria and virus infected cells they encounter and recognize?
macrophages
What was the surprising result in Fredrick Griffitths experiment?
I am not entirely sure about "surprising" but his experiment showed that bacteria can transfer genetic information through a process known as transformation.
Where did scientist think traits were inherited through before the Hershey and chase experiment?
They knew traits were inherited, but did not know why.
What did the experiments of griffith Avery and Hershey and chase show?
The first major experiment that led the discovery of DNA as the genetic material was performed by Griffith and Avery. They studied 2 strains of bacteria "Streptococcus Pneumonia, which causes pneumonia. They found that one strain could be transformed into other forms of bacteria and germs.
How do you get the plague?
One gets plague when he/she is bitten by infected rats or fleas.You got it through a flea that has bitten a rat whos blood is infected with many bad bacteria, like yersinia pestis.
How do you Summarize griffith's transformation experiments?
Frederick Griffith introduced the Griffith experiment in 1928. This experiment proved that bacteria can carry genetic information through a process called transformation.
How do you get Cough?
Whooping cough(or pertussis) is caused by a bacteria called Bordetella pertussis. When an infected person coughes or sneezes, the bacteria moves through the air. This is the reason Pertussis is an extremely contagious disease.
What is the mode of transmission in Bacterial Pneumonia?
droplet inhalation.
