A mature duplicated chromosome consists of:

  • A. Two identical double helical DNA molecules
  • B. Two different double helical DNA molecules
  • C. A double helical DNA molecule distributed in both chromatids
  • D. Histone chains wrapped around DNA core

Explanation

Replication is semi conservative and highly accurate, so the two sister chromatids each hold a complete double helix and the two are identical copies joined at the centromere. They are not different molecules, which is what distinguishes sister chromatids from homologous chromosomes. Note also that DNA wraps around the histones rather than the other way round, which makes the last option backwards.

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