A parent DNA molecule with both strands labeled with heavy nitrogen ( $15N^{15}\text{N}$ ) is transferred to a growth medium containing only light nitrogen ( $14N^{14}\text{N}$ ) and allowed to undergo three rounds of replication.

Which of the following statements correctly predict the results if DNA replication is semiconservative?

After one round of replication, 100% of the DNA molecules have an intermediate hybrid density ( $15N/14N^{15}\text{N}/^{14}\text{N}$ ).
After two rounds of replication, there is an equal proportion of intermediate density ( $15N/14N^{15}\text{N}/^{14}\text{N}$ ) molecules and light density ( $14N/14N^{14}\text{N}/^{14}\text{N}$ ) molecules.
After three rounds of replication, 75% of the DNA molecules have intermediate hybrid density ( $15N/14N^{15}\text{N}/^{14}\text{N}$ ) and 25% have light density ( $14N/14N^{14}\text{N}/^{14}\text{N}$ ).

Which of the following statements correctly predict the results if DNA replication is semiconservative?

After one round of replication, 100% of the DNA molecules have an intermediate hybrid density ( $15N/14N^{15}\text{N}/^{14}\text{N}$ ).
After two rounds of replication, there is an equal proportion of intermediate density ( $15N/14N^{15}\text{N}/^{14}\text{N}$ ) molecules and light density ( $14N/14N^{14}\text{N}/^{14}\text{N}$ ) molecules.
After three rounds of replication, 75% of the DNA molecules have intermediate hybrid density ( $15N/14N^{15}\text{N}/^{14}\text{N}$ ) and 25% have light density ( $14N/14N^{14}\text{N}/^{14}\text{N}$ ).

Nucleotides and nucleic acids

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Nucleotides and nucleic acids

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