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

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

After three rounds of replication, 75% of the double-stranded DNA molecules are of heavy density ( $15N/15N^{15}\text{N}/^{15}\text{N}$ ).
After four rounds of replication, the ratio of hybrid-density ( $14N/15N^{14}\text{N}/^{15}\text{N}$ ) to heavy-density ( $15N/15N^{15}\text{N}/^{15}\text{N}$ ) DNA molecules is $1 : 8$ .
After three rounds of replication, 12.5% of the individual polynucleotide strands in the population contain $14N^{14}\text{N}$ .

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

After three rounds of replication, 75% of the double-stranded DNA molecules are of heavy density ( $15N/15N^{15}\text{N}/^{15}\text{N}$ ).
After four rounds of replication, the ratio of hybrid-density ( $14N/15N^{14}\text{N}/^{15}\text{N}$ ) to heavy-density ( $15N/15N^{15}\text{N}/^{15}\text{N}$ ) DNA molecules is $1 : 8$ .
After three rounds of replication, 12.5% of the individual polynucleotide strands in the population contain $14N^{14}\text{N}$ .

Nucleotides and nucleic acids

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Nucleotides and nucleic acids Questions