DNA Structure and Replication

ID #2223

Is the 10nm fiber just the histone core and the winded dna around it (the nucleosome) or is it more than that? The lecture notes for chapter 13 show a 10nm fiber a string with 3 nuclesomes and some other things with it, but in the book the dimension of each nucleosome is 10nm so I don't see how that thing could be considered just 10nm.


A 10nm fiber contains a series of chromatosomes that are separated by approximately 50 bp of linker DNA. A chromatosome contains the 8 core histones (2 molecules each of H2A, H2B, H3 and H4) along with the H1 protein holding the nucleosome together. (Chromatosomes contain the 146/147 bp that are wrapped around the core histones as well as approximately 20 bp of DNA that contacts H1, so a total of 166 bp). A 10nm fiber gets its name from the approximately width of a nucleosome, not the length. The 10/11 nm width of a nucleosome includes the wound DNA as well. 

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