Contact Information
Department of Physics525 Northwestern Avenue
West Lafayette, IN
47907-2036
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Telephone:
(765) 494-2970
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(765) 494-0706
Professor Steven M. Block
Sigma Xi Distinguished Lecture
February 19, 2004
Fowler Hall, Stewart Center
Stewart Center Gallery, Stewart Center
Professor Steven M. Block
Department of Applied Physics and
Department of Biological Sciences
Stanford University
"Light and Life: Biophysics, One Molecule at a Time"
Optical tweezers, also called optical traps, represent the closest we’ve come to realizing the “tractor beam” familiar from science fiction. Optical tweezers derive their trapping ability from radiation pressure, generated by a beam of infrared laser light focused through a strong lens. They can grasp and manipulate microscopic particles in the size range of nanometers to micrometers, and can apply piconewton-scale forces with exquisite control. With a judicious choice of laser power and wavelength, optical tweezers are non-damaging to trapped objects, even to living specimens such as cells or bacteria. But optical tweezers have found their greatest utility thus far in vitro, in the new research area being called single molecule biophysics, where they are used to study the nanomechanical properties of individual biomolecules. This talk will highlight recent experimental progress using optical tweezers in studies of the nanoscale motions of the eukaryotic motor protein kinesin, which transports cellular cargo along microtubules, and also in studies of transcriptional elongation by prokaryotic RNA polymerase, the enzyme that transcribes the genetic code with such great fidelity, synthesizing mRNA molecules from the DNA template.