Why is DNA replication described as semiconservative?

• A. Each daughter DNA molecule contains one original (parental) strand and one newly synthesized strand.
• B. The parental DNA molecule remains intact, and an entirely new double-stranded DNA molecule is produced separately.
• C. Both strands in each daughter DNA molecule are entirely newly synthesized after replication.
• D. Only the coding regions of DNA are replicated, while noncoding regions are conserved without replication.

Answer: (A)

Verified step by step guidance

1. Understand the structure of DNA: DNA is composed of two complementary strands forming a double helix, where each strand serves as a template during replication.
2. Recall the process of DNA replication: The double-stranded DNA unwinds, and each original (parental) strand acts as a template for the synthesis of a new complementary strand.
3. Define 'semiconservative replication': This means that each new DNA molecule consists of one original (parental) strand and one newly synthesized strand.
4. Contrast semiconservative replication with other models: In conservative replication, the original DNA molecule remains intact and a completely new molecule is made; in dispersive replication, both strands are mixtures of old and new DNA.
5. Conclude why DNA replication is semiconservative: Because after replication, each daughter DNA molecule conserves one parental strand paired with one new strand, ensuring genetic continuity.