Which term describes the DNA replication result where each new molecule contains one old strand and one new strand?

• A. Conservative replication
• B. Dispersive replication
• C. Semi-conservative replication
• D. Replicative duplication

Answer: (C)

During DNA replication, the way parental DNA is distributed into the daughter molecules determines the outcome. In semi-conservative replication, each new double helix contains one strand from the original molecule and one newly synthesized strand. The parental strands separate, each serving as a template for a new complementary strand, so two daughter molecules arise, each with one old strand and one new strand. This was supported by experiments showing intermediate densities after replication, consistent with one old and one new strand per molecule. In contrast, a conservative model would keep both original strands together in one molecule while forming a completely new double helix in the other, and a dispersive model would mix old and new DNA segments within both strands.