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Unformatted text preview: es apart. And our
genes would be s ilent without the s ervices of m es s enger RNA, which carries genetic ins tructions over to the
cellâ€™s protein-m aking factories . The m ovem ents that m ake thes e cellular activities pos s ible occur along a
com plex network of threadlike fibers , or polym ers , along which bundles of m olecules travel like tram s . The
engines that power the cellâ€™s freight are three fam ilies of proteins , called m yos in, kines in and dynein. For
fuel, thes e proteins burn m olecules , of ATP, which cells m ake when they break down the carbohydrates and
fats from the foods we eat. The energy from burning ATP caus es changes in the proteins â€™ s hape that allow
them to heave them s elves along the polym er track. The res ults are im pres s ive: In one s econd, thes e
m olecules can travel between 50 and 100 tim es their own diam eter. If a car with 5-foot-wide engine were as
efficient, it would travel 170 to 340 km ph.
Ronald Vale, a res earcher at the Howard Hughes Medical Ins titute and the Univers ity of California at San
Francis co, and Ronald Milligan of the Scripps Res earch Ins titute have realis ed a long-awaited goal by
recons tructing the proces s by which m yos in and kines in m...
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This document was uploaded on 03/23/2014.
- Summer '14