Why is DNA replication described as semiconservative?

• A. Each daughter DNA molecule contains two newly synthesized strands and no parental strands.
• B. Each daughter DNA molecule contains two parental strands that separate from the original duplex and remain paired together.
• C. Each daughter DNA molecule contains one parental (old) strand and one newly synthesized strand.
• D. The parental DNA molecule remains completely intact, and an entirely new DNA molecule is synthesized separately.

Answer: (C)

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 structure of DNA: DNA is a double helix composed of two complementary strands, each serving as a template during replication.
3. Define semiconservative replication: In semiconservative replication, each of the two daughter DNA molecules contains one original (parental) strand and one newly synthesized strand.
4. Contrast semiconservative replication with other models: The conservative model suggests the parental DNA remains intact and a completely new molecule is made, while the dispersive model suggests both strands are mixtures of old and new DNA.
5. Explain why semiconservative replication is correct: Experimental evidence (e.g., Meselson-Stahl experiment) showed that after replication, DNA molecules consist of one old strand paired with one new strand, preserving half of the original molecule in each daughter DNA.