Alfred Hershey and Martha Chase experiment description
Answers
They use p32 and s35 for radiolabelling. P32 --dna ands35 --protein
ANSWER:-
Viral infection (Hershey and Chase Experiment)
◇ Bacteriophage is virus which infect bacteria .
◇ T2 is a common virus that attacks E.coli .
◇ T2 phages have two structural components DNA and protein.
◇ After the infection, the virus multiplies within the bacterium.
◇ Hershey and Chase tried to find out which is the genetic material.
◇ They identified the genetic material by blender experiment involving radioactive labeling.
◇ In 1952, Alfred Hershey and Martha Chase made two preparations of T2 phage.
◇ In one preparation the proteins were labelled with S35.
◇ In the second preparation the DNA was labelled with P32.
◇ Both of them were used separately to infect E.coli.
◇ Just after infection the E.coli cells were gently agitated in a blender to separate the phage particles from the bacteria.
◇ Then the culture was centrifuged, as the heavier bacterial cells formed a pellet at the bottom.
◇ The lighter viral components outside the bacterial cells remained in the supernatant.
◇ Hershey and Chase found that when the viral protein was labelled with S35 the radioactivity remained in the supernatant.
◇ This showed that the viral proteins have not entered the bacterial cells during infection.
◇ But when the viral DNA was labelled using P32 the radioactivity was found in the bacterial pellet.
◇ This showed that the viral DNA entered the bacterial cell during infection.
◇ This viral DNA causes the multiplication of the phage inside the bacterium.
