Single molecules and single cells are the fundamental building blocks in biology. Facilitated by the advancement of technology, quantitative single-molecule and single-cell measurements provide a unique perspective toward many biological systems by revealing individual stochasticity and population heterogeneity. Taking advantage of these approaches, we studied chromosome organization and gene expression in bacteria and discovered new biophysical mechanisms: chromosome organization by a nucleoid-associated protein in live bacteria, and transcriptional bursting by the regulation of DNA supercoiling in bacteria.
