DNA Packaging

In eukaryotes, double-stranded DNA is organized inside a membrane-bound nucleus to fit within the cell’s limited space.

At the first level of compaction, DNA wraps tightly around specific proteins called histones.

A histone core with DNA wrapped around it forms a nucleosome, the basic unit of DNA packaging. The linker histone binds at the DNA entry and exit points, helping to stabilize and compact the structure.

Nucleosomes are connected by linker DNA, forming a structure that resembles beads on a string.

At the next level of packaging, nucleosomes and linker DNA fold together to form chromatin fibers.

Finally, additional fibrous proteins compact the chromatin even further. This allows long DNA molecules to remain structured as chromatin, which becomes highly condensed into visible chromosomes during cell division.