Simplify the following text for a Grade 9 native English-speaking person.
Original: Nucleosomes are folded through a series of successively higher order structures to eventually form a chromosome ; this both compacts DNA and creates an added layer of regulatory control which ensures correct gene expression .
Simplified: Nucleosomes are folded , in a series of higher order structures , to form a chromosome . This folding compacts the DNA and adds a layer of regulatory control .