One of the key ideas in biophysics is that structure determines property determines function. On the PHYS3170 blog one of the students, Alex (aka. ack!) had a profound observation about chapter 11 of Nelson. Here is my paraphrase/version/extension of her point. Today both biology teaching and research is driven by a paradigm: first determine the biomolecular structure, then deduce the relevant properties of the structure, and then explain the function of the biomolecule. However, historically this is NOT how biology has operated, and Nelson illustrates this nicely when considering the case of molecular ion pumps and the mitochondria. One starts with a knowledge of the biological function, e.g., energy production and distribution, and one then deduces what physical property the system must have (e.g., the ability to maintain a non-equilibrium concentration gradient of ions), and one then makes a hypothesis about what kind of structure is necessary to have this property (e.g., an ion pu