in the classic meselson and stahl experiment e coli are first grown in 15n enriched media 0th ge

In the Meselson and Stahl experiment, E. coli are first grown in 15N-enriched media, which means

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In the classic Meselson and Stahl experiment, E. coli is first grown in 15N-enriched media (0th generation) and subsequently switched to 14N-enriched media. A DNA sample isolated during the first generation of E. coli grown in 14N media is subjected to a centrifugation step in a dense CsCl gradient. Assuming that replication occurs in a semi-conservative fashion, the DNA sample will:____________ a) run as two bands (of equal intensity), one at the same position as a uniformly 15N-labeled DNA, and one at the same position as a uniformly 14N-labeled DNA. b) run as one band, at the same position as a uniformly 15N-labeled DNA. c) run as one band, at the same position as a uniformly 14N-labeled DNA. d) run as one band, at a position expected for DNA containing a 14N:15N ratio equal to 7. e) run as one band, at a position expected for DNA containing a 14N:15N ratio equal to 1.

          In the classic Meselson and Stahl experiment, E. coli is first grown in 15N-enriched media (0th generation) and subsequently switched to 14N-enriched media. A DNA sample isolated during the first generation of E. coli grown in 14N media is subjected to a centrifugation step in a dense CsCl gradient.
Assuming that replication occurs in a semi-conservative fashion, the DNA sample will:____________
a) run as two bands (of equal intensity), one at the same position as a uniformly 15N-labeled DNA, and one at the same position as a uniformly 14N-labeled DNA.
b) run as one band, at the same position as a uniformly 15N-labeled DNA.
c) run as one band, at the same position as a uniformly 14N-labeled DNA.
d) run as one band, at a position expected for DNA containing a 14N:15N ratio equal to 7.
e) run as one band, at a position expected for DNA containing a 14N:15N ratio equal to 1.

Added by Elizabeth A.

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