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 made by randomly mixing short segments of old and new DNA throughout both strands.
• C. Each daughter DNA molecule contains two newly synthesized strands and none of the parental strands.
• D. The parental DNA molecule remains intact, and an entirely new double-stranded copy is produced separately.

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: the double helix unwinds, and each original (parental) strand serves 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: conservative replication would keep the original molecule intact and produce a completely new molecule, while dispersive replication would mix old and new DNA segments within each strand.
5. Conclude that DNA replication is described as semiconservative because each daughter DNA molecule conserves one parental strand paired with one new strand.