A nucleosome is about 10nm in diameter. It consists of 8 histone protein molecules forming two circles stuck together like two halves of an Oreo cookie. The DNA in a nucleosome loops around the protein cookie twice. Nucleosomes look like beads on a string when viewed in the TEM using appropriate staining.
Work Step by Step
All of this can be obtained by reviewing the material on p. 328 in Fig. 16.22.