What is the main idea of the passage?

Cells package DNA through dynamic layers of proteins, nucleosomes, chromatin, loops, and chromosomes while preserving controlled access. (The passage traces nested packaging and repeatedly emphasizes the balance between compaction, movement, and access.)

Why does chromatin condense further before cell division?

Greater compaction helps copied DNA move and separate with less entanglement. (The third paragraph links the extra condensed form with moving duplicated material safely during division.)

What does “dynamic” mean in the second paragraph?

able to change its organization in response to conditions (The colon explains that sections can become more accessible or compact as needs change.)

What proteins does DNA wrap around first?

histones (The second paragraph identifies histone groups as the proteins around which the double helix wraps.)

How DNA Fits Inside a Cell: Level 5 Reading Comprehension Questions

A eukaryotic cell's DNA contains an enormous molecular chain relative to the space that holds it. Fitting that chain into a nucleus cannot be like stuffing loose thread into a pocket. Random tangling would obstruct copying, repair, and the controlled use of genes. Cells instead organize DNA through several nested levels of packaging.

The double helix wraps around groups of proteins called histones, forming units known as nucleosomes. A string of nucleosomes folds and interacts with additional proteins to create chromatin. Loops of chromatin attach to organizing structures and occupy regions within the nucleus. The arrangement is dynamic: sections can become more accessible or more compact as cellular needs change.

Before many cells divide, DNA is copied and the chromatin condenses further into visible chromosomes. Compaction helps the duplicated material move without becoming hopelessly entangled. After division, much of it relaxes again. A chromosome is therefore not always a rigid X-shaped object; that familiar form represents one especially condensed stage.

Packaging also influences access. Proteins that read or copy DNA must reach particular sequences, so chemical marks and remodeling systems help open or close local regions. Compact does not mean silent forever, and open does not mean active at every moment. The organization is orderly without resembling a single perfect spool. Chromatin bends, loops, and shifts within a crowded nucleus. Its success lies in balancing contradictory needs: DNA must be compressed yet reachable, protected yet changeable, and separated during division without losing the information encoded along its length.

Comprehension questions