The broad-ranging topic of this Minisymposium attracted four presentations describing in vivo and in vitro experimental work and two presentations that primarily addressed theoretical aspects of chromatin behavior over long and short length scales. Overall, the focus was very much on chromosomes, with presentations addressing chromosome ends (telomeres), centromeres, chromosome segregation, heterochromatin, and specific gene regions. In two complementary papers from the Andrew Spakowitz laboratory, Peter Mulligan and Elena Koslover (Stanford University), addressed theoretical models of DNA mechanics across the very different length scales in chromosomes and cooperative binding during heterochromatin formation. The theme of nucleosome structure and packing was maintained by Abbas Padeganeh (Universite de Montreal), who used total internal reflection fluorescence–coupled, photobleaching-assisted copy-number counting of single nucleosomes obtained from cultured cells to provide evidence to support the view that the histone H3 variant CENP-A, which is critical for centromere identity and function, forms octameric nucleosomes containing dimers of CENP-A. Geoff Lovely (Caltech, Pasadena) addressed the molecular mechanism that generates antigenic variation by using a single-molecule in vitro assay to capture and characterize pairing intermediates in V(D)J recombination mediated by RAG1-2 and HMGB1. David Sherratt (Oxford University) described in vivo single-molecule biochemistry experiments addressing the architecture of the Escherichia coli SMC (Structural Maintenance of Chromosomes) complexes, MukBEF, and its role in chromosome segregation. Clusters of relatively immobile dimer-of-dimer MukBEF complexes associate with the replication origin region to apparently position it and facilitate the positioning of newly replicated sisters. Finally, Daniela Rhodes (Nanyang Technological University) presented the first three-dimensional structure of active, full-length human telomerase determined using single-particle electron microscopy. Telomerase is medically important, as telomere maintenance in the majority of cancer cells involves the activation of telomerase. Telomerase consists of a large RNA subunit TER and a protein catalytic subunit TERT. The structural information revealed that telomerase has a bilobal architecture in which the two monomers in the dimer have “open” and “closed” conformations, linked by a flexible dimer interface. Fitting of the atomic structure of the beetle TERT subunit into the electron microscopy density revealed the spatial relationship between RNA and protein subunits, providing novel insights into the architecture of the telomerase enzyme. Furthermore, Rhodes presented data showing that catalytic activity requires both TERT active sites to be functional, providing unambiguous evidence that human telomerase functions as a dimer.