Which method of DNA replication produces molecules with one parental strand and one new strand?

Which method of DNA replication produces molecules with one parental strand and one new strand?

• A. Semiconservative replication
• B. Conservative replication
• C. Dispersive replication
• D. Replication fork

Answer: (A)

DNA copying is best described by how the old strands are used as templates to build new ones. In semiconservative replication, the two parental strands separate and each serves as a template for a new complementary strand. The outcome is two DNA molecules, each consisting of one original (parental) strand and one newly synthesized strand. This pattern matches what is observed in experiments that track the fate of old versus new DNA across replication rounds, such as the classic Meselson–Stahl results showing intermediate-density daughter molecules after one round. Conceptually, this process happens at the replication fork, where helicase unwinds the double helix and DNA polymerase extends new strands in the 5' to 3' direction, producing a leading strand continuously and a lagging strand in fragments that are later joined. The alternative models would yield different patterns: a completely old plus completely new double helix (conservative) or DNA consisting of mixed old and new segments within both molecules (dispersive), neither of which align with the observed outcomes.

DNA copying is best described by how the old strands are used as templates to build new ones. In semiconservative replication, the two parental strands separate and each serves as a template for a new complementary strand. The outcome is two DNA molecules, each consisting of one original (parental) strand and one newly synthesized strand. This pattern matches what is observed in experiments that track the fate of old versus new DNA across replication rounds, such as the classic Meselson–Stahl results showing intermediate-density daughter molecules after one round.

Conceptually, this process happens at the replication fork, where helicase unwinds the double helix and DNA polymerase extends new strands in the 5' to 3' direction, producing a leading strand continuously and a lagging strand in fragments that are later joined. The alternative models would yield different patterns: a completely old plus completely new double helix (conservative) or DNA consisting of mixed old and new segments within both molecules (dispersive), neither of which align with the observed outcomes.