Current Topics in Biophysics (SC/BPHS 2090 3.0) Lew Lectures | Jerzak Lectures | Guest Lectures |
course syllabus [in pdf format]
Lew Lectures
- Course Notes and Readings for the Lew Lectures are mounted on Moodle [link] and E-Reserves[link]
- Course Evaluations for the Lew Lectures are available for 2010 [pdf], 2011 [pdf], 2012 [pdf], 2013 [pdf] and 2014 [pdf]
GROWTH AND FORM: Allometry [01]
growth and life cycle dimensional analysis The relations between organismal size, life cycle and physiological function (metabolism, etc.) will be introduced to form a general overview of the physical envelope of organismal life.
GROWTH AND FORM: Biomechanical Constraints on Growth and Form [02]
the height of a jump the height of a tree The relations of force and motion will be explored in the context of 'defying' gravity (to explain why fleas and humans are able to jump to the same height). The height of a tree relates to growing high to optimize light collecting for photosynthesis, the strength of materials and how they limit height, and the need to supply water to the topmost regions of the tree, all constrained by physical limits.
DIFFUSION, ADVECTION AND BIOLOGICAL PUMPS: The Evolution of Multi-Cellularity [03]
Diffusion: Thermodynamic and molecular explanations from Einstein Einstein's explanation, a derivation from a two-dimensional random walk, was the starting point for a physical explanation of the diffusive flux of neutral solutes, in solution (Fick's equations).Time Dependence The constraints on biological organisms as a consequence of the slowness of diffusion over long distances will be presented.
DIFFUSION, ADVECTION AND BIOLOGICAL PUMPS: Advection and the Peclet Number
Laminar flow at low Reynolds number Nutrient supply by diffusion or advection As multicellular organisms evolved, their size increased. This creates a challenge: How to supply nutrients at sizes where diffurion is too slow. Advective flow can work, the Peclet number compares the relative contributions of advection and diffusion.Volvox is used as a case study of the utility of advective flow for a relatively simple multi-cellular form.Biological pump mechanisms causing advective flow The remarkable diversity of advective pumps in biological organisms is outlinedXylem feeding insects Cicadas and spittlebugs are used as an example of a relatively simple valve-less chamber pump
MOLECULAR MOTORS: Cellular Movement [04]
Reynold's number: Laminar and turbulent flow Viscosity and drag Small sizes, low velocities and viscosity create a very different physical 'universe' for small versus large organisms.
MOLECULAR MOTORS: Bacterial Motility [05]
Rotatory engines Chemiosmotics (energetics) Vectorial movement of hydronium ions passing through the stator/rotor causes rotatory motion of the flagella and thus bacterial motility.
READINGS for Lew Lectures
Provided on e-reserves [link] or on the Moodle website [link] for the course.
West, Geoffrey B. and James H. Brown (2004) Life's universal scaling laws. Physics Today (September) pp. 36-42.
McMahon, Thomas (1973) Size and shape in biology. Science 179:1201-1204;
Tyree, Melvin T. (2003) Tree hydraulics. Nature 423:923.
