He level of dna packaging brought about by the formation of looks like beads on a string.

The level of DNA packaging which is brought about by the formation of nucleosomes it looks like beads on a string.
In general terms, nucleosomes are termed as a basic unit of DNA packaging which is in eukaryotes. 
It consists of eight segments of DNA wound. Nucleosomes form a fundamental unit which repeats the eukaryotic genomes to the nucleus by ensuring a well appropriate access to it.

The answer is nucleosomes in which a part of DNA that is wrap with proteins. In the nucleus the DNA forms with proteins that is called chromatin allowing the DNA to condense into a minute volume. Under the microscope this structure looks like a bead on a string.