核小体，核粒：在真核细胞中组蛋白与DNA的任何复合物，在电子显微镜下为DNA链上的珠状小体
The nature of the nucleosome. A nucleosome contains a protein core made of eight histone molecules. As
indicated, the nucleosome core particle is released from chromatin by digestion of the linker DNA with a nuclease, an enzyme that breaks down DNA. (The nuclease can degrade the exposed DNA but cannot attack the DNA wound around the nucleosome.) After dissociation of the isolated nucleosome into its protein core and DNA, the length of the DNA that was wound around the core can be determined. Its length of 146 nucleotide pairs is sufficient to wrap almost twice around the histone core.