Date/Time
Date(s) - 04/02/2015
3:30 pm - 4:30 pm

Title: Two illustrations of the importance of diffusion in biological systems

Speaker: Dr. Cecile Fradin

Institute: McMaster University

Location: ABB 102

Description:

In living systems thermal motion becomes preponderant when one reaches the nanometre scale, thus protein diffusion plays an important role in cells. But how do stochastic motions at the molecular scale add up to create the exquisite order observed at the cellular scale? In my first example, I will present the case of Bicoid, a protein that acts as a postal code by letting cells know where they are located in the fly embryo. We demonstrated that diffusion of Bicoid drives the amazingly robust and precise formation of large-scale protein concentration gradients, as proposed by Francis Crick in 1970. In my second example, I will discuss the increasingly recognized role of non-thermal â??biologicalâ? stochastic noise in augmenting certain diffusion processes.
The rotational diffusion of magnetotactic bacteria is one of the systems where biological noise has been invoked to explain observations, and I will discuss whether it is appropriate to treat it as a purely physical system, i.e. a collection of small magnets.