Why is DNA replication described as semiconservative?

• A. Each daughter DNA molecule contains one parental (old) strand and one newly synthesized strand.
• B. Each daughter DNA molecule is composed entirely of newly synthesized DNA strands.
• C. The parental DNA remains intact and a completely separate copy is made without using the original strands as templates.
• D. Only one of the two parental DNA strands is replicated while the other remains unchanged and unpaired.

Answer: (A)

Verified step by step guidance

1. Understand the structure of DNA: DNA is double-stranded, with two complementary strands running in opposite directions.
2. Recall the process of DNA replication: during replication, the two strands of the parental DNA molecule separate and serve as templates for the synthesis of new complementary strands.
3. Define semiconservative replication: each new DNA molecule consists of one original (parental) strand and one newly synthesized strand.
4. Compare the semiconservative model to other models: in conservative replication, the original DNA molecule remains intact and a completely new molecule is made; in dispersive replication, the new DNA strands are mixtures of old and new DNA segments.
5. Conclude why DNA replication is semiconservative: because each daughter DNA molecule conserves one parental strand paired with one new strand, ensuring genetic continuity.