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What does semiconservative DNA replication mean?

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Diagram of a DNA polynucleotide chain showing linked deoxyribose sugars, phosphate groups, and nitrogenous bases (adenine, guanine, cytosine, thymine), with an inset comparing ribose and uracil in RNA. — Nucleic acid A portion of the polynucleotide chain of deoxyribonucleic acid (DNA), with an inset showing the corresponding pentose sugar and pyrimidine base in ribonucleic acid (RNA).

Semiconservative DNA replication is the process by which a double-stranded DNA molecule replicates to produce two exact copies, each consisting of one original parent strand and one newly synthesized strand.12

During this process, the two strands of the parent double helix separate, and each serves as a template for the formation of a new, complementary strand. Because each resulting daughter molecule retains one of the original strands, the process is termed "semiconservative".1342

This mechanism was famously confirmed by the 1958 experiments of Matthew Meselson and Franklin Stahl. By using heavy and light isotopes of nitrogen to label DNA strands in Escherichia coli, they demonstrated that daughter cells contained DNA molecules composed of one "heavy" (parental) strand and one "light" (newly synthesized) strand. This templating process is fundamental to biology, as it ensures that genetic information is accurately replicated and passed down through generations.42