1. Physics 414: Introduction to Biophysics Professor Henry Greenside November 7, 2017

2. Weekly problem solving session
Completely optional, goal is to provide some extra time to solve problems, work on homework, ask questions about course material
Either Wed 5:30 – 6:30 pm or Mon 4:30 – 5:30 pm
Location to be announced on Piazza
Start this Wednesday if possible

3. Start discussion of Chapter 13 on diffusion “A Statistical View of Biological Dynamics”
Chapter 8 on random walk descriptions of biomolecules assumed thermodynamic equilibrium, macroscopic details did not change in time.
Chapter 13 continues and extends discussion to non-equilibrium, time-dependent spatially varying concentrations. Mathematical description leads to so-called diffusion equation.

4. At the blackboard: key equations

5. Definition of a flux vector J for some class of moving objects

6. Worked example of flux

7. Fick’s first law and the flux vector for particles moving with a well-defined velocity

8. Mathematical statements of particle conservation for diffusion, mass conservation for a fluid

9. Conservation of particle number and Fick’s first law gives a diffusion equation

10. Advection-diffusion equation for diffusion in a fluid

11. Qualitative question 1 about diffusion

12. Qualitative question 2 about diffusion

13. One-minute End-of-class Question