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Storage of Genetic Information

Most of an animal's genetic information is stored in the DNA in its chromosomes. As you can imagine, storing this much information takes a lot of DNA. In fact, the DNA in a typical human nucleus stretches over a meter in length! So how does all of this DNA fit in a nucleus? You can unpack the chromosome in this animation to find out.

American scientists Olins and Woodcock discovered that chromosomes contain what are referred to as supercoils. These supercoils are formed from the twisting and packing of smaller coils, which are also known as chromatin fiber. The chromatin fiber, in turn, consists of a somewhat irregular left-handed super helix containing six nucleosomes per turn. Each nucleosome is made up of DNA wound around small groups of proteins called histones.

Thus, chromatin is comprised of DNA, which contains the genetic material, and protein, which is involved in folding and twisting the DNA to make it more compact. Unpacked DNA is 10,000 times longer than chromosomal DNA.