Even with 'mixed fibers' chromatin does not change its 3-D structure
"Interphase" refers to the period in the cell cycle in which chromosomes spend most of their time. During this phase, in between mitoses, chromosomes live "dissolved'' in the nucleus where they carry out the processes required for the duplication of genetic material. Our current knowledge regarding the behaviour of chromosomes during interphase is unfortunately quite limited; for example, we would need to know more about the three-dimensional structure of the chromatin filament - the long molecule that makes up the chromosomes and that consists of DNA and other proteins - and how it changes in time and space. The shape of the chromosome is in fact important for its function as it allows or prevents access to portions of genetic code for the duplication processes.