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Possible Models for DNA Replication


Three possible ways in which DNA can replicate are illustrated. The two original strands of DNA are shown in yellow (light); newly synthesized DNA is blue (dark).

To explain the phenomenon of heredity, biological information must be accurately copied and transmitted from each cell to all of its progeny. Three ways for DNA molecules to replicate may be considered, each obeying the rules of complementary base pairing.

  • Conservative replication would leave intact the original DNA molecule and generate a completely new molecule.
  • Dispersive replication would produce two DNA molecules with sections of both old and new DNA interspersed along each strand.
    • Semiconservative replication would produce molecules with both old and new DNA, but each molecule would be composed of one old strand and one new one.

    The replication is semiconservative. Each strand acts as a template for the synthesis of a new DNA molecule by the sequential addition of complementary base pairs, thereby generating a new DNA strand that is the complementary sequence to the parental DNA. Each daughter DNA molecule ends up with one of the original strands and one newly synthesized strand.

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