Semi-conservative replication explains how DNA is copied, checked, amplified or analysed through specific strand relationships, enzyme functions and molecular techniques.
Coverage 2014–2024 · Updated 16 Jul 2026
Semi-conservative replication produces DNA molecules in which each double helix contains one parental strand and one newly synthesized strand.
When the original strands separate, each acts as a template. Complementary base pairing preserves information while retaining one physical strand from the original molecule in each product.
Identify a product by checking: one old strand; one new strand; complementary pairing between them.
After one round, heavy parental DNA in a density experiment is replaced by two intermediate molecules, each containing one old and one new strand.
Semi-conservative does not mean half the bases are copied randomly; the strand pattern is the key prediction.
This objective is assessed through structured response, commonly using Explain / Outline / Distinguish.
Explain / Outline / Distinguish / Identify / State
Build the answer around this relationship: Semi-conservative replication depends on matching each strand, enzyme or laboratory step to its exact function.
Saying both parental strands stay together instead of one parental strand entering each daughter molecule.
Representative question
Outline the reason that DNA replication is described as semi-conservative.
DNA replication produces exact DNA copies before cell division and maintains genetic continuity for reproduction, growth, and tissue replacement. Semi-conservative replication gives each new DNA molecule one original strand and one new strand; complementary base pairing and Meselson-Stahl isotope evidence support the model. Helicase unwinds DNA and breaks hydrogen bonds; DNA polymerase joins complementary nucleotides to build new strands. PCR amplifies selected DNA using primers, temperature cycles, and Taq polymerase; gel electrophoresis separates DNA fragments by size and charge. PCR and gel electrophoresis support DNA profiling for forensic identification and paternity testing.
