This animation shows how DNA molecules are packed up into chromosomes.

DNA is tightly packed up to fit in the nucleus of every cell. As shown in the animation, a DNA molecule wraps around histone proteins to form tight loops called nucleosomes. These nucleosomes coil and stack together to form fibers called chromatin. Chromatin, in turn, loops and folds with the help of additional proteins to form chromosomes. Condensing DNA into chromosomes prevents DNA tangling and damage during cell division.

Depending on students’ background, it may be helpful to pause the animation at various points to discuss different structures.