Which statement describes the relationship between the two new DNA molecules produced during replication?

Which statement describes the relationship between the two new DNA molecules produced during replication?

• A. They Are Identical to the Original and to Each Other
• B. They Are Completely New Copies
• C. They Contain No Original Strands
• D. They Are Opposite in Sequence

Answer: (A)

This question tests semiconservative replication—the idea that each new DNA molecule contains one parental strand and one new strand. Because DNA polymerases use each old strand as a template, the new strand is built to be complementary, so the sequence on the new molecule matches the original. As a result, the two daughter molecules end up with the same overall sequence as the original DNA, and they are identical to each other as well. The notion that both copies are entirely new, that they contain no original strands, or that they would have opposite sequences doesn’t fit how replication preserves the genetic information.

This question tests semiconservative replication—the idea that each new DNA molecule contains one parental strand and one new strand. Because DNA polymerases use each old strand as a template, the new strand is built to be complementary, so the sequence on the new molecule matches the original. As a result, the two daughter molecules end up with the same overall sequence as the original DNA, and they are identical to each other as well. The notion that both copies are entirely new, that they contain no original strands, or that they would have opposite sequences doesn’t fit how replication preserves the genetic information.