This book was written, to a not inconsiderable degree, on the basis of the course "The Problems of Modern Biophysics" which the author gives to the students and postgraduates of the Biophysical Department at Moscow University School of Physics. It is meant for those who have a sufficiently good background in physics as well as in biology. I have tried to make this book intelligible to a broader circle of readers, i.e., to physicists not competent enough in biology, and to biologists not competent enough in physics. I hope that I have succeeded. This book is neither a textbook nor a systematic...