Answer:
In eukaryotes, nucleosomes play major roles in chromatin organization and gene expression
Step-by-step explanation:
In eukaryotic organisms, chromosomal DNA is packaged with the help of proteins called 'histones' to form chromatin. The nucleosomes represent the basic packing units of the chromatin. Each nucleosome is composed of a histone octamer containing each two histones H2A, H2B, H3 and H4 wrapped around by 147 bp of DNA. Nucleosomes act as scaffolds to form higher-order chromatin structures (i.e., 30-nm chromatin fibers and condensed chromosomes). Moreover, nucleosome histone proteins can be chemically modified at defined amino acid residues, and thus nucleosomes also provide an epigenetic layer of information that can promote or inhibit gene expression.