DNA包装

In eukaryotes, double-stranded DNA is specially organized within a membrane-bound nucleus to accommodate the cell's limited space.

At the first level of compaction, DNA is wrapped tightly around specific proteins called histones. A histone core and the DNA wrapped around it are together known as a nucleosome, the basic unit of DNA packaging. Nucleosomes are joined together by linker DNA to resemble beads on a string. In the next level of packaging, nucleosomes and linker DNA coil to form chromatin fibers.

Finally, additional fibrous proteins compact the chromatin even further, allowing such long lengths of DNA into such tightly-condensed units recognized as chromosomes, depending on the phase of cell division.