Arrange the following steps of the Hershey and Chase experiment in correct sequence:
(A) Labelling of some bacteriophages with radioactive phosphorus and some with radioactive sulfur.
(B) Agitating in blender followed by centrifugation.
(C) Infecting E. coli in two batches with two differently labelled bacteriophages.
(D) Identification of radioactivity in supernatant and sediment
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (C), (B), (D)
Hershey and Chase grew phages labelled with radioactive phosphorus or sulphur (A), let them infect E. coli in two batches (C), blended and centrifuged the cultures (B), and then looked for radioactivity in the supernatant and sediment (D).
NCERT Extract:
The Genetic Material is DNA – “… They grew some viruses on a medium that contained radioactive phosphorus and some others on medium that contained radioactive sulfur.”
The Genetic Material is DNA – “Radioactive phages were allowed to attach to E. coli bacteria. Then, as the infection proceeded, the viral coats were removed from the bacteria by agitating them in a blender. The virus particles were separated from the bacteria by spinning them in a centrifuge.”