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•  Chromosomes replicate in interphase before meiosis

Interphase is an active period that precedes meiosis and involves key events needed to prepare the cell for successful division

DNA is replicated during the S phase of interphase, resulting in chromosomes that contain two identical DNA strands

  • These genetically identical strands are called sister chromatids and are held together by a central region called the centromere
  • These chromatids separate during meiosis II, becoming independent chromosomes each made of a single DNA strand

If DNA replication did not occur prior to meiosis there would be no need for a 2nd meiotic division (meiosis I = diploid 
→ haploid)

  • The fact that DNA replication does occur suggests that meiosis evolved from mitosis (where initial DNA replication is necessary)
  • One benefit of the duplication of chromatids is that it increases the potential for genetic recombination to occur (more variation)

Chromosome Replication and Separation During Meiosis

meiotic interphase