DNA replication is described as semiconservative. Which statement best explains what semiconservative replication means after one round of replication?

• A. Each daughter DNA double helix is a mosaic in which both strands are mixtures of old and new DNA segments.
• B. Each daughter DNA double helix contains one parental (old) strand and one newly synthesized strand.
• C. Each daughter DNA double helix contains two parental (old) strands paired together.
• D. Each daughter DNA double helix contains two newly synthesized strands, and the parental DNA remains intact as a separate molecule.

Answer: (B)

Verified step by step guidance

1. Understand the concept of DNA replication: DNA replication is the process by which a cell copies its DNA before cell division, ensuring each daughter cell receives an identical set of genetic information.
2. Recall the meaning of 'semiconservative' replication: In semiconservative replication, each new DNA molecule consists of one original (parental) strand and one newly synthesized strand.
3. Analyze the options given: The correct explanation should reflect that after replication, each daughter DNA double helix has one old strand and one new strand, not a mixture within strands or two old strands together.
4. Eliminate incorrect options: The option stating that strands are mosaics of old and new segments is incorrect because strands are continuous, not patchworks; the option with two old strands or two new strands only is also incorrect based on the semiconservative model.
5. Conclude that the best explanation is that each daughter DNA double helix contains one parental (old) strand and one newly synthesized strand, which aligns with the semiconservative replication model.