Oded Agam (Hebrew University of Jerusalem) | The dynamics of living cells from the viewpoint of a statistical physicist |
Abstract:
Deciphering the cellular metabolic network is, perhaps, the most prominent objective of cell biology. It is a formidable enigma because the metabolic network is an extremely complicated system. It comprises several thousand different compounds with intricate interactions among them that are, essentially, unknown.
There are two complementary viewpoints of living cells. One is to view the cell as a large computer designed to respond effectively to environmental changes. The second is to consider the cell as a complex physical system obeying physical statistics laws. The first viewpoint encouraged the effort of disentangling the metabolic network structure by identifying specific modules such as metabolic cycles, pathways, and forms of regulations. However, this reductionism approach can only take you so far because all network components are strongly intertwined. Hence, a holistic approach is required.
Recent experimental data, obtained by Balaban’s group, show that the recovery time of E. coli cells, after their growth was arrested by acute stress, exhibits distinctive statistical features typical of complex physical systems. These include a memory of the period that the cell was subjected to the stress and slow power-law decay of the distribution of single-cell recovery time. The same features are common to systems that exhibit physical “aging”, such as amorphous polymers, stretched DNA, paper crumpling, colloidal solutions, spin glasses, supercooled liquids, and coulomb glasses.
This observation suggests that a relatively simple statistical model can describe the cell in the acute stress regime. In this talk, I will present a simple spin model that reproduces the experimental observations. In particular, I will show that the statistics of the cells' recovery times are obtained from the statistics of the crossing problem of a random walker in a potential field and present its solution.
When: February 23, 2022 02:00 PM (Israel Standard Time).
Where: Room 223, Multipurpose Bldg. & over Zoom