What does semiconservative replication mean for the composition of daughter DNA molecules?

• A. Each daughter DNA molecule contains one parental template strand and one newly synthesized strand
• B. Both daughter strands are newly synthesized
• C. The parental molecule remains intact as duplicated
• D. Energy is not required in this process

Answer: (A)

Semiconservative replication means that after copying, each daughter DNA molecule contains one strand from the original molecule and one newly synthesized strand. The two strands of the parent separate, and each serves as a template for a new complementary strand, with nucleotides added to pair with the template. So, every daughter molecule ends up with one old (parental) strand and one new strand.

This precisely matches the idea that a DNA copy preserves half of the original in each daughter molecule. The other options don’t fit because, in this model, both strands aren’t newly made, and the original molecule isn’t left intact as a single duplicated unit; rather, it is unwound and used to generate two new duplexes. Also, DNA replication requires energy to form phosphodiester bonds and to unwind the double helix, so the statement claiming no energy is required isn’t correct.