(a) State the reasons for which Hershey and Chase carried out their
experiments.
(b) Answer the following questions based on the experiments of
Hershey and Chase:
(i) Name the different radioactive isotopes they used, and explain how they used them.
(ii) Why did they need to agitate and spin their culture?
(iii) Write their observations and the conclusions they arrived at.
Answers
Answer:
a) To find out about what exactly is the transforming principle or the genetic material that is transferred down the hierarchy they performed this experiment.
b)
1. S 32 and P35 were the radioactive isotopes used in their experiment.
2. The need to agitate and spin the culture was because they has to remove the viral coat once the contents were transferred.
3. Hershey and Chase concluded that DNA, not protein, was the genetic material. They determined that a protective protein coat was formed around the bacteriophage, but that the internal DNA is what conferred its ability to produce progeny inside a bacterium.
Hope it helps..
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Hershey and Chase carried out the experiment to prove that DNA is the genetic material and not proteins.
Explanation:
a. Hershey and Chase proves that DNA is the genetic material. They disapprove that proteins are not the genetic material.
b. (i) Hershey and Chase use Phosphorous-32 to label the DNA and Sulphur-35 to label the proteins in bacteriophage (viruses that infect the bacterium). Then they use bacteriophage to infect the bacteria. It was found that protein coat labelled with S-35 does not incorporate in the bacterium, instead DNA labelled with P-32 gets incorporated.
(ii) They spin and agitate their culture in order to remove the viral coat after all the contents are transferred.
(iii) They concluded that DNA is the genetic material and not the protein.