Bases form the sequence information of DNA (top). Two complimentary strands of DNA bond together to give a double helix (right). DNA double helixes are highly packaged around histones to form a chromosome ultrastructure (centre).
DNA and chromatin structure is a highly complex arrangement which allows more than 2m of DNA to be packaged into every cell of the human body. Naked DNA wraps around histone protein complexes to form 10nm chromatin structures that look like beads on a string. These histone octamers then associate via the H1 subunit to form the coiled 30nm solenoid structure. This complex strand then folds in on itself many times to create the dense arrangement seen in chromosomes during cell division.