Biophysics of protein–DNA interactions and chromosome organization

•Review of mechanical properties of DNA and DNA–protein complexes.•Pedagogical presentation of statistical-mechanics of DNA response to tension and twist.•Discussion of DNA topology and topology control in cells.

The function of DNA in cells depends on its interactions with protein molecules, which recognize and act on base sequence patterns along the double helix. These notes aim to introduce basic polymer physics of DNA molecules, biophysics of protein–DNA interactions and their study in single-DNA experiments, and some aspects of large-scale chromosome structure. Mechanisms for control of chromosome topology will also be discussed.