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Which of the following correctly orders the size relationship of repeating units along the chromatin fibre, from smallest to largest packaging level?

  • A Chromosome, then nucleosome, then chromatin fibre, then finally the DNA double helix itself
  • B DNA double helix, nucleosome, chromatin fibre (beads on string and higher coiling), chromosome
  • C Nucleosome, then chromosome, then the DNA double helix, then finally the chromatin fibre itself
  • D Chromatin fibre, then chromosome, then nucleosome, then finally the DNA double helix itself

Correct answer: B. DNA double helix, nucleosome, chromatin fibre (beads on string and higher coiling), chromosome

Explanation: Packaging proceeds from the naked DNA double helix wrapping around histones to form nucleosomes (beads on a string), which further coil into chromatin fibres, which condense further to form a visible chromosome.

Concept context

DNA structure, replication, transcription, translation, the genetic code, and gene regulation (lac operon). The single most important chapter for NEET molecular biology.

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