DNA replication is described as semi conservative because each daughter molecule

  • A. contains one old strand and one newly synthesised strand
  • B. is built entirely from new nucleotides
  • C. conserves only half of its original bases
  • D. is rebuilt only in every second cell cycle

Explanation

When the two parental strands separate, each serves as a template for a new partner, so both daughter helices retain one original strand. This was proved by Meselson and Stahl using nitrogen isotopes, ruling out models in which old DNA was chopped up or fully conserved.

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