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 beginnings of a brain first become apparent around four weeks after conception when the neural plate folds to form the neural tube