A mature duplicated chromosome consists of:
Correct answer: A. Two identical double helical DNA molecules
- 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.
This question appeared on the UHS MDCAT 2025 paper, which you can sit online with every answer explained.
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About Chromosomes
Chromosomes are DNA-protein structures that carry genes and become visible during cell division. Coverage includes chromatin, centromeres, sister chromatids, homologous chromosomes, chromosome number, and the distinction between diploid and haploid cells, with links to DNA replication, mitosis and meiosis.
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