The Hershey and Chase experiments involved the preparation of two different types of radioactively labeled phage. Which of the f
ollowing best explains why two preparations were required?A. The bacteriophage used in the experiments was a T2 phage.B. It was necessary that each of the two phage components, DNA and protein, be identifiable upon recovery at the end of the experiment.C. Each scientist had his own method for labeling phage, so each conducted the same experiment using a different isotope.D. Establishing the identity of the genetic material required observation of two phage generations.
The correct answer is B.It was necessary that each of the two phage components, DNA and protein, be identifiable upon recovery at the end of the experiment
Explanation:
Hershey and chase in his experiment lebelled the T₂ bacteriophage with radioactive sulfur and radioactive phosphorus separately. Then they infect E.coli with T₂phage and separated phage from bacteria by centrifugation.
Because DNA contains phosphorus not protein, cells infected with phage containing radioactive phosphorous showed radioactivity bacause DNA enters the cell not protein confirming DNA is the genetic material and radioactive sulfur was found in supernatant.
In HIV-infected patients, there is a gradual loss of CD4+ T cells over time. These cells, also called T helper cells, organize the immune system's attack on disease-causing invaders, like Salmonella.
