Why is DNA replication described as semiconservative?

• A. The parental DNA molecule is conserved intact, and an entirely new double-stranded DNA molecule is made separately.
• B. Each daughter DNA molecule contains one original (parental) strand and one newly synthesized strand.
• C. Each daughter DNA molecule contains two newly synthesized strands and no parental DNA.
• D. Each daughter DNA molecule contains two parental strands that separate but are not copied.

Answer: (B)

Verified step by step guidance

1. Understand the concept of DNA replication: DNA replication is the process by which a cell copies its entire DNA before cell division, ensuring each daughter cell receives a complete set of genetic information.
2. Recall the structure of DNA: DNA is double-stranded, with two complementary strands running in opposite directions, held together by base pairing.
3. Define 'semiconservative replication': In semiconservative replication, each of the two new DNA molecules contains one original (parental) strand and one newly synthesized strand.
4. Contrast semiconservative replication with other models: The conservative model suggests the parental DNA remains intact and a completely new molecule is made, while the dispersive model suggests strands are mixed; semiconservative replication differs because it conserves one parental strand in each daughter molecule.
5. Conclude why DNA replication is described as semiconservative: Because after replication, each daughter DNA molecule is composed of one strand from the original molecule and one newly synthesized strand, preserving half of the original DNA in each new molecule.