In semiconservative DNA replication, what does it mean that replication is “semiconservative”?

• A. Each daughter DNA molecule contains one parental (old) strand and one newly synthesized strand.
• B. The parental DNA molecule is broken into fragments, and these fragments are randomly distributed into the daughter molecules.
• C. Each daughter DNA molecule contains two newly synthesized strands, and the parental DNA remains intact.
• D. Each daughter DNA molecule contains two parental (old) strands and no newly synthesized DNA.

Answer: (A)

Verified step by step guidance

1. Understand the term 'semiconservative' in the context of DNA replication. It refers to how the original DNA strands are used during the replication process.
2. Recall that DNA is double-stranded, and during replication, the two strands separate and serve as templates for new strands.
3. Recognize that in semiconservative replication, each new DNA molecule consists of one original (parental) strand and one newly synthesized strand.
4. Contrast this with other possible models: conservative replication (where the original DNA remains intact and a completely new molecule is made) and dispersive replication (where parental DNA is broken into fragments and mixed randomly).
5. Conclude that the semiconservative model means each daughter DNA molecule conserves one parental strand paired with one new strand, ensuring genetic continuity.