Which of the statements about nucleosomes are correct?
a. most histones are large (more than 250 amino acid residues), acidic proteins rich in lys and arg.
b. degradation of linker dna yields dna fragments of about 200 bp.
c. dna binding to histones enables overall positive supercoiling without enzymes that underwind the dna helix.
d. partial enzymatic digestion of chromatin results in dna fragments of about the histones h2a, h2b, h3, and h4 make up the nucleosome octamer that binds dna.
e. histone proteins are positioned on dna, in part, based on the abundance of clusters of base pairs in dna.