How Long Is a Strand of DNA When Unwound?

The DNA stored in each human cell has a total length of about 6 feet, according to the Theoretical and Computational Biophysics Group at the University of Illinois. The DNA is stored inside a cell's nucleus so tightly that it only occupies 10 percent of the total cellular volume.

The basic unit of DNA packaging in eukaryotic cells is a nucleosome, which consists of a DNA segment wrapped in sequence around eight histone protein cores. The nucleosomes are folded through a series of higher order structures, which eventually form a chromosome. Human cells are diploid, and have 22 different types of autosomal chromosomes presenting as two copies. Each cell also contains two sex chromosomes. In nearly every human cell, the approximately 6 feet of DNA is segmented throughout this 46 chromosome total.