Arrange the given steps of the Hershey and Chase experiment in correct sequence.
(A) Separation of virus particles from bacteria by centrifugation
(B) Infection of bacteria with phage DNA
(C) Radioactive bacteriophages were allowed to attach the bacteria
(D) Removal of viral coat from bacteria by blending
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (C), (B), (D), (A)
(C) Radioactive bacteriophages were allowed to attach the bacteria — first. Hershey and Chase grew one set of phages with radioactive phosphorus (which labels DNA) and another with radioactive sulfur (which labels protein). These labelled phages were then put with E. coli so that they could attach.
(B) Infection of bacteria with phage DNA — second. After attaching, the phage sends its genetic material into the bacterial cell. The protein coat stays outside.
(D) Removal of viral coat from bacteria by blending — third. As the infection went on, the bacteria were agitated in a blender. This shook off the empty viral coats still sticking to the outside of the bacteria.
(A) Separation of virus particles from bacteria by centrifugation — last. Spinning in a centrifuge separated the light virus particles from the heavier bacteria. Only the bacteria infected by phages with radioactive DNA turned out radioactive, which showed that DNA is the genetic material.
NCERT Extract:
The Genetic Material Is DNA – …
