Double-stranded DNA loops around 8 histones twice, forming the nucleosome, which is the building block of chromatin packaging. DNA can be further packaged by forming coils of nucleosomes, called chromatin fibers. These fibers are condensed into chromosomes during mitosis, or the process of cell division.
Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.
During DNA packaging, long pieces of double-stranded DNA are tightly looped, coiled, super coiled, and folded so that they fit easily within the cell. This highly compacted DNA is then arranged into structures called chromosomes.