Eukaryotic genomes: organization, regulation, and evolution: chromatin structure is based on successive levels of dna packing. A. eukaryotic dna is precisely combined with large amounts of protein. B. eukaryotic chromosomes contain an enormous amount of dna relative to their condensed length. Each human chromosome averages about 1. 5 108 nucleotide pairs. If extended, each dna molecule would be about 4 cm long, thousands of times longer than the cell diameter. C. the chromosomes fit into the nucleus through an elaborate, multilevel system of. D. histone proteins are responsible for the first level of dna packaging. The mass of histone in chromatin is approximately equal to the mass of. Their positively charged amino acids bind tightly to negatively charged. The five types of histones are very similar from one eukaryote to another, and similar proteins are found in prokaryotes. The conservation of histone genes during evolution reflects their pivotal role in organizing dna within cells.