= Hershey-Chase experiment
{c}
The \b[Hershey-Chase experiment] distinguished the behavior of <DNA> and coat <proteins> during infection by <Bacteriophage T2>. In their 1952 study, <A. D. Hershey> and <Martha Chase> followed <phosphorus-32> associated with phage <DNA> and <sulfur-35> associated with phage <proteins>. The labels made chemically different parts of the same kind of <virus> experimentally distinguishable.<Independent functions of viral protein and nucleic acid in growth of bacteriophage by A. D. Hershey and Martha Chase>[Abstract, points 1 and 4–8; pp. 50–53]{ref}
After the <bacteriophages> attached to <bacteria>, a Waring blender sheared off much of the material remaining outside the <biological cells>. <Centrifugation> separated a cell-containing sediment from the surrounding liquid. Most sulfur label stayed outside, whereas most phage phosphorus remained with the <biological cells>; the treated <bacteria> could still yield progeny <bacteriophages>. Comparing label in progeny supplied a further test beyond attachment alone.<Independent functions of viral protein and nucleic acid in growth of bacteriophage by A. D. Hershey and Martha Chase>[Abstract, points 4–6; p. 52, progeny-label comparison]{ref}
An original accounting example illustrates the logic: if a tracer gives 80 corrected units with cells and 20 outside, its cell-associated fraction is $80/(80+20)=0.8$. Comparing that fraction for the two labels tests their different destinations. It does not measure an 80-percent share of heredity. Label specificity, incomplete separation and recovery matter.
The result supports entry of <DNA> while much coat <protein> remains external. It neither establishes that every protein molecule stays outside nor excludes all other entering material. The paper explicitly limits further chemical inferences.<Independent functions of viral protein and nucleic acid in growth of bacteriophage by A. D. Hershey and Martha Chase>[Abstract, points 5 and 8]{ref}
Back to article page
