(nu body) A nodule, some 7-10nm in diameter, consisting of * histones , around which is wrapped a strand of DNA about 150 base pairs long. One type of histone, H1, is positioned between adjacent nucleosomes and may serve to clamp the DNA in position. By wrapping around histone beads, the total length of DNA is condensed by a factor of some seven times. Supercoiling of the string of nucleosome beads results in a further condensation. Nucleosomes are thus of considerable importance in packaging enormous lengths of DNA into minute chromosomes. |
