▁cond ensed ▁chrom atin . ▁ ▁The ▁primary ▁protein ▁components ▁of ▁chrom atin ▁are ▁hist ones , ▁which ▁bind ▁to ▁DNA ▁and ▁function ▁as ▁" anch ors " ▁around ▁which ▁the ▁str ands ▁are ▁w ound . ▁In ▁general , ▁there ▁are ▁three ▁levels ▁of ▁chrom atin ▁organization : ▁ ▁DNA ▁wra ps ▁around ▁hist one ▁prote ins , ▁forming ▁nucle os om es ▁and ▁the ▁so - called ▁" be ads ▁on ▁a ▁string " ▁structure ▁( e uch rom atin ). ▁ ▁Multiple ▁hist ones ▁wrap ▁into ▁a ▁ 3 0 - nan ometer ▁fib re ▁consisting ▁of ▁nucle os ome ▁arrays ▁in ▁their ▁most ▁compact ▁form ▁( h eter och rom atin ). ▁ ▁High er - level ▁DNA ▁super co iling ▁of ▁the ▁ 3 0 - nm ▁fi ber ▁produces ▁the ▁met aph ase ▁chrom os ome ▁( d uring ▁mit osis ▁and ▁me ios is ). ▁ ▁Many ▁organ isms , ▁however , ▁do ▁not ▁follow ▁this ▁organization ▁scheme . ▁For ▁example , ▁s perm ato zo a ▁and ▁av ian ▁red ▁blood ▁cells ▁have ▁more ▁tight ly ▁pack ed ▁chrom atin ▁than ▁most ▁e uk ary otic ▁cells , ▁and ▁try pan os om at id ▁proto zo a ▁do ▁not ▁con den se ▁their ▁chrom atin ▁into ▁visible ▁chrom os om es ▁at ▁all . ▁Pro k ary otic ▁cells ▁have ▁entirely ▁different ▁structures ▁for ▁organ izing ▁their ▁DNA ▁( the ▁pro k ary otic ▁chrom os ome ▁equivalent ▁is ▁called ▁a ▁gen oph ore