The Grandpierre Lecture - Christine Keating
The Grandpierre Lecture
"Polymer solutions as a model cytoplasm in primitive artificial cells based on lipid vesicles"
Presented by Christine Keating, Penn State University
Abstract: Chemists have long sought to understand the natural world through synthesis. In our lab, we carry on this tradition not by making and breaking chemical bonds but rather by preparing simple experimental models of biological cells based on physical and materials chemistry. This lecture will describe efforts to prepare artificial cells and cell-like environments that capture one or more key features of their living counterparts.
The interior of biological cells is crowded with macromolecules, heterogeneous in composition, and dynamic. These aspects of intracellular environments dramatically impact their physical chemistry and are crucial to cell function. In our simple model systems, macromolecular crowding is provided by polymers such as polyethylene glycol or dextran (a polyglucose). When both polymers are present at sufficient concentrations, the solution can phase separate to form two distinct aqueous phases, each enriched in one of the polymers. Aqueous phase separation is common in macromolecule solutions and has been observed in living cells. In our work, the formation of dextran-rich and PEG-rich phase domains provides control over the local concentration of not only the polymers themselves but also any molecules that accumulate in one of the phases by partitioning. This compartmentalization of nucleic acids or proteins can be used to drive reactions that are concentration dependent.
Encapsulation of the aqueous two-phase systems within lipid vesicles having a semipermeable membrane provides a primitive model of biological cells capable of microcompartmentalization, polarity, and asymmetric division. The synthesis and characterization of artificial cells and cell-like environments may provide new insight into how fundamental chemical and physical phenomena common to all cells may have shaped the development of early cells and could still underlie many of the seemingly complex behaviors of modern cells.
Hosted by the Chandler Society
Thursday, February 21, 2013 at 4:30pm
Room 209 Havemeyer
Tea & cookies will be served prior to the seminar in room 328 Havemeyer