Eukaryotic chromosome structure

This level of packaging includes the wrapping of DNA around proteins called histones in order to form condensed nucleosomes.

Later, chemist Alexander Todd determined that the backbone of a DNA molecule contained repeating phosphate and deoxyribose sugar groups.

High resolution X-ray images of DNA that were obtained by Maurice Wilkins and Rosalind Franklin suggested a helical, or corkscrew like shape.

Scientists also discovered plant and animal cells have a central compartment called the nucleus.

They soon realized chromosomes were found inside the nucleus and contained different information for many different traits.

The scientists used hundreds of measurements of where different parts of the DNA get close to one another to help create this model.

Higher-order packaging is accomplished by specialized proteins that bind and fold the DNA.

This generates a series of loops and coils that provide increasingly higher levels of organization and prevent the DNA from becoming tangled and unmanageable.