DNA replication is referred to as semiconservative because, during the process of replication, each new double-stranded DNA molecule consists of one original (parental) strand and one newly synthesized strand. This concept was elegantly demonstrated by the Meselson-Stahl experiment in the 1950s, which provided clear evidence for the semiconservative model.
In simpler terms, when DNA replicates, the two strands of the DNA helix separate. Each individual strand serves as a template for the creation of a new complementary strand. As a result, each daughter DNA molecule formed during replication is composed of one strand from the original DNA (the ‘conserved’ strand) and one newly formed strand. This mechanism ensures that the genetic information is accurately copied and passed on to the daughter cells.
The term ‘semiconservative’ highlights that only half of the parental DNA is conserved in each new molecule, rather than being completely preserved or fully discarded. This process is crucial for maintaining the integrity of genetic information across generations of cells.