What term describes the nature of DNA replication in which each double helix contains one parental strand and one newly synthesized strand?

The term that accurately describes the nature of DNA replication in which each double helix contains one parental strand and one newly synthesized strand is "semi-conservative." This model of replication was established through experiments that showed that when DNA replicates, each of the two resulting double helices consists of one original (parental) strand and one newly synthesized strand. This process ensures that genetic information is accurately passed on during cell division, as each new cell receives a complete set of genetic instructions.

In contrast, the conservative model would imply that one double helix remains completely intact while a wholly new double helix is synthesized, which does not happen in DNA replication. The dispersive model suggests that segments of the parental DNA are interspersed with new DNA in both strands, which also does not reflect the actual process. "Directional" does not specifically pertain to the replication mechanism itself but rather describes the orientation of the DNA strands. Thus, "semi-conservative" is the most accurate description of how DNA replication occurs.