Abstract

The various models of chromatin fiber folding that have been proposed over the years are considered and evaluated. It is concluded that the radial loop / scaffold model is strongly supported by the available evidence, although the term ‘scaffold’ may be an unfortunate one. The scaffold is not a solid rod running the length of the chromatid but rather appears to be an aggregation of discrete anchoring complexes for the loops of the fiber. Despite support for this model, there is a need for more evidence to resolve the questions that remain.