# Physics 5005 - Biological Physics (Nieves)

### Text

- Biological Physics, D. Nelson (Freeman)

### Grading

Grading will depend on performance in periodic problem sets, a midterm exam and a final exam, with the following weights:

- Homework: 40%
- Midterm exam: 30%
- Final exam: 30%

### Homeworks

By all means you may work in groups on the homework assignments. Collaboration is an important part of learning and of scholarship in general. However, each student must turn in her or his own writeup of the solutions. If two individual writeups are nearly identical, neither will receive credit. In fairness to your fellow students, late homework will not be accepted.

This course is an introduction to the applications of physics to living systems for students with a physics background. The central theme of the course is to discuss how living systems generate order, with a focus on physical principles and biological examples. Topics include the properties the physics of random walks and diffusion, low-Reynolds number hydrodynamics, entropy and free energy, entropic forces and self assembly. Selected biophysics applications will be discussed based on student interest.

### Contents

- Basic physical concepts
- Dimensional Analysis
- Forces (example of Aquiles Tendon)
- Hydrostatics
- Viscocity
- Shear
- Exponential Growth and Decay
- Exponential growth
- Exponential decay
- Exponential growth
- Plots
- Generalizations (Newton's cooling law)
- Logistic growth
- Statistical Mechanics
- Postulate of Statistical Mechanics
- Distribution functions
- Thermodynamic quantities
- The Boltzman factor
- Example calculations
- The ideal gas law
- The Nernst relation
- Pressure variation in the atmosphere
- Brwonian movement
- Difussion
- Flux
- Continuity equation
- Fick's law
- Einstein relation between difussion and viscocity
- The difussionion equation in one dimension
- Steady-state solutions
- Transport
- Membranes
- Osmotic presure in a liquid
- Volume transport through a membrane
- The articial kidney example
- Flow through a pore
- Membranes
- Donan equilibirum
- Ions in a solution
- Ion movement: the Nernst-Plank relation
- Goldman equation
- The resting nerve cell
- Electrical properties of nerves
- Coulomb's law
- Potential and Voltage
- Conductors and dielectrics
- Current and Ohm's law
- The Hodgin-Huxley model for the membrane current
- Propagation of a nerve impulse