Whip it good: how flagella help cells move

The linked article is for SIAM News, the magazine for members of the Society for Industrial and Applied Mathematics (SIAM). However, even though the main audience for this magazine is professional mathematicians, I wrote it to be understandable even if you gloss over the math.

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A Mathematical Tale of Fibers, Fluids, and Flagella

For SIAM News:

Under a microscope, a cell scoots along by its own power and hoovers up small crumbs of nutrition from the water around it. An example of such an organism is a choanoflagellate, which has a thin, whip-like appendage called a flagellum that controls its feeding and motion. While similarly proportioned apparatuses would be useless on a human scale, flagella are common among single-celled organisms like bacteria, the sometimes-toxic dinoflagellate algae, and even human sperm cells.

Motion in the microscopic world—particularly in fluids—involves an entirely different set of forces than those that govern macroscopic environments. Flagella operate efficiently under these forces and allow microscopic life to move around in fluids, where large viscous forces are present even in substances such as water. The motion of choanoflagellates and the way in which flexible fibers or strands of cells passively respond to liquid flow all constitute a set of complex problems with many potential applications in engineering and medicine.

“With the advent of microfluidic devices and computational technology, there has been an incredible resurgence in studies of the flow of tiny creatures at the microscale,” Lisa Fauci, an applied mathematician at Tulane University and a former president of SIAM, said. “There are possibilities of creating nanorobots that can be guided with external magnetic fields to break up blood clots or deliver drugs to a tumor.”

Read the rest at SIAM News