Which statement best describes the semiconservative nature of DNA replication?

Which statement best describes the semiconservative nature of DNA replication?

• A. Two new strands
• B. One old strand and one new strand
• C. Two old strands
• D. Each new molecule contains one old strand and one new strand

Answer: (D)

In semiconservative replication, each of the two daughter DNA molecules ends up with one strand conserved from the original molecule and one newly synthesized strand. As the double helix unwinds, each parent strand serves as a template for a new complementary strand, so both resulting molecules contain one old strand and one new strand. That’s why the best description is that every new molecule has one old and one new strand—this explicitly states that this composition applies to both daughter molecules. Descriptions that say both strands are new or both are old contradict how replication actually proceeds, and saying just “one old strand and one new strand” can be less precise about the fate of both daughter molecules.

In semiconservative replication, each of the two daughter DNA molecules ends up with one strand conserved from the original molecule and one newly synthesized strand. As the double helix unwinds, each parent strand serves as a template for a new complementary strand, so both resulting molecules contain one old strand and one new strand. That’s why the best description is that every new molecule has one old and one new strand—this explicitly states that this composition applies to both daughter molecules. Descriptions that say both strands are new or both are old contradict how replication actually proceeds, and saying just “one old strand and one new strand” can be less precise about the fate of both daughter molecules.