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In
order to determine which of these models was true, the
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following
experiment was performed: The original DNA
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strand
was labelled with the heavy isotope of nitrogen,
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N‑15.
This DNA was allowed to go through one round of
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replication
with N‑14, and then the mixture was
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centrifuged
so that the heavier DNA would form a band
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lower
in the tube, and the intermediate (one N‑15 strand
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and
one N‑14 strand) and light DNA (all N‑14) would
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appear
as a band higher in the tube. The expected results
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for each model
were:
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