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나노과학기술대학원에서는 김용운 박사 (Korea Institute for Advanced Study) 세미나를 개최합니다.


 * 일시/장소  : 4월 12일(월) 오전 11시~ , 자연과학동(E6) 2층세미나실 2502호  



Title : Understanding cooperativity in biological systems: Swimming bacteria and DNA packaging 




Rapidly increasing attention to life science nowadays makes it challenging and promising that physics interfaces with

biological sciences and nanotechnology, at the outside the conventional boundaries of the scientific disciplines.

In particular, it is of great interest from a physical point of view that using unique features like self-organization and

conformational flexibility, biological systems display various cooperative phenomena. Here I will introduce a couple

of examples of the cooperative phenomena and my contributions to its understanding. The first one is bacteria swimming, especially, using cilia, that clearly demonstrates very different principles of propulsion on the micro/nano-meter scale from

the macroscopic world. Nonlinear deformation of the soft object in response to hydrodynamic flow is a key factor to have

net propulsion by breaking time-reversal symmetry. Furthermore, phase locking between swimming objects is found to

occur autonomously, yielding significantly enhanced swimming efficiency. This finding provides an interesting physical

explanation on self-organized synchronization and its role in bacteria swimming. Secondly, I will discuss condensation

of charged biopolymers, which is in fact surprising and puzzling phenomena in sharp contrast with the common sense

that like charges always repel. For example, DNA is a highly, negatively charged biopolymer, but these likely-charged

DNA usually form strongly condensed phases. According to several recent experiments, DNA condensations are

effectively driven by short stiff polyamines such as spermine and spermidine. A novel energetic bridging mechanism

explaining the prevailing role of polyamines on the charged biopolymer condensation will be presented.



 나노과학기술대학원 책임교수 신중훈 배상.