(A) Mitotic structure of chromosomes in yeast (Ai) and metazoans (Aii). (Ai) In yeast, condensin compacts the rDNA and tethers the rDNA to the centromere. The centromere-proximal side of the rDNA is enriched for condensin, which compacts chromosomes through loop extrusion. (Aii) In metazoans there are two condensin complexes, which function on different scales (condensin I: shorter loops, condensin II: longer loops). Together, condensin I and II compact chromosomes through loop extrusion, forming nested loop structures. (B) Interphase structure of chromosomes in yeast (Bi) and metazoans (Bii). (Bi) In yeast, condensin compacts chromosomes through loop extrusion and aids clustering of tRNAs and transposons by promoting long-range interactions. (Bii) In metazoans, condensin compacts chromosomes through loop extrusion, clusters transposons and enhancer-promoter pairs by promoting long-range interactions, and aids the formation of TADs.