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Why can copied DNA need to be unlinked?

Making a copy and separating the copies are different problems. Circular DNA molecules can remain linked like two closed rings, even though each is a distinct molecule. Research on E. coli distinguishes that linking from a knot within one DNA molecule. The difference helps explain why the geometry of DNA matters alongside its genetic information.

5–7 min

Questions you could explore

  • Why can bending two linked, closed loops fail to separate them?
  • How does linking between molecules differ from twisting or knotting within a molecule?

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