DNA replication is called semiconservative because which statement best describes the composition of each daughter DNA molecule after replication?

• A. Each daughter DNA molecule contains two parental strands and no newly synthesized strands.
• B. Each daughter DNA molecule contains one parental (old) strand and one newly synthesized strand.
• C. The parental DNA molecule remains intact, and an entirely separate copy is synthesized without using the parental strands as templates.
• D. Each daughter DNA molecule contains two newly synthesized strands and no parental strands.

Answer: (B)

Verified step by step guidance

1. Understand the concept of semiconservative DNA replication: during replication, the two strands of the parental DNA molecule separate, and each serves as a template for the synthesis of a new complementary strand.
2. Recognize that after replication, each daughter DNA molecule consists of one strand from the original (parental) DNA and one newly synthesized strand.
3. Recall that this mechanism ensures genetic continuity because each new DNA molecule retains one original strand, reducing the chance of errors during replication.
4. Contrast semiconservative replication with other hypothetical models: conservative replication (parental strands stay together, new strands form a separate molecule) and dispersive replication (both strands are mixtures of old and new DNA).
5. Conclude that the correct description of semiconservative replication is that each daughter DNA molecule contains one parental (old) strand and one newly synthesized strand.