The length of DNA in one chromosome The packaging of DNA in eukaryotic chromosomes or how you change this... The length of DNA in one chromosome 4 cm into this... Too small to show the real size, but you could fit 10,000 along the length of a fingernail! 0.2-2 µm

Link to 3D animation of the packaging of DNA into chromosomes

Level 1: Nucleosomes or ‘beads on a string’ Linker DNA Histone proteins form a complex

Level 2: Chromatin fibre Nucleosomes coil and stack

Level 3: Looped fibres Chromatin fibre loops along the protein scaffold Protein scaffold

Level 4: More folds to make the most compacted chromosome Looped chromatin fibre folds The most condensed form of DNA packaging during metaphase. Replication has just occurred so the image shows two chromatids 0.2-2 µm