This book covers some subjects that we find inspiring when teaching physics students about biology. The book presents a selection of topics centered around the physics/biology/chemistry of genes. The focus is on topics that have inspired mathematical modeling approaches. The presentation is rather condensed, and demands some familiarity with statistical physics from the reader. However, we attempted to make the book complete in the sense that it explains all presented models and equations in sufficient detail to be self-contained. We imagine it as a textbook for the third or fourth years of a physics undergraduate course.

Throughout the book, in particular in the introductions to the chapters, we have expressed basic biology ideas in a very simplified form. These statements are meant for the physics student who is approaching the biological subject for the first time. Biology textbooks are necessarily more descriptive than physics books. Our simplified statements are meant to reduce this difference in style between the two disciplines. As a consequence, the expert may well find some statements objectionable from the point of view of accuracy and completeness. We hope, however, that none is misleading. One should think of these parts as first-order approximations to the more complicated and complete descriptions that molecular biology textbooks offer. On the other hand, the physical reasoning that follows the simplified presentation of the biological system is detailed and complete.