Physics of Small DNA Loops
| Date/Time: | Monday, 01 Dec 2014 from 4:10 pm to 5:00 pm |
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| Location: | Physics 0003 |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
Abstract: Small DNA loops are both structurally and functionally important to biology. It takes energy to form them and a force to keep them. In this talk, I will explain how we study the energetics of sharp DNA bending using small DNA loops. Using single-molecule Fluorescence Resonance Energy Transfer (FRET), we measure the lifetime of a DNA loop as a function of loop size. Above a critical loop size, the loop lifetime changes with loop size in a manner consistent with elastic bending stress, but below it, becomes less sensitive to loop size, indicative of DNA softening. Our result thus sets the limit of elastic bending at ~7 degrees per base pair. Time permitting; I will also present a new computational method to obtain the equilibrium distribution of forces exerted by a semi-flexible polymer loop.