KEY TERMS

centromere

telomere

plasmid

DNA supercoiling

supercoiled DNA

relaxed DNA

DNA topology

closed-circular DNA

DNA underwinding

linking number (Lk)

superhelical density (σ)

negative supercoiling

positive supercoiling

topoisomer

writhe (Wr)

twist (Tw)

plectonemic supercoiling

solenoidal supercoiling

topoisomerase

type I topoisomerase

type II topoisomerase

catenane

SMC protein

cohesin

condensin