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SUMMARY:Flicking dynamics of monotrichous bacteria - Michael Gomez (Univer
 sity of Cambridge)
DTSTART:20191205T130000Z
DTEND:20191205T140000Z
UID:TALK135664@talks.cam.ac.uk
CONTACT:Anne Herrmann
DESCRIPTION:Many species of bacteria possess a single helical flagellar fi
 lament\, which is connected to a motor embedded in the cell body via a sho
 rt flexible segment known as a ‘hook'. As the motor rotates it winds up 
 the hook\, and this twist is in turn transmitted to the filament\, which r
 otates the filament and leads to a propulsive force on the cell body. Howe
 ver\, this propulsive force only allows the cell to swim forwards or backw
 ards along a straight path (in the absence of noise)\; to change direction
  and efficiently explore their environment\, several species of marine bac
 teria have been observed to exploit a strategy known as ‘flicking'. Flic
 king is an elastic instability in which the hook buckles under the compres
 sive force generated by the filament and forms a kink\, which acts to rota
 te the cell before the hook eventually unbuckles and the cell resumes stra
 ight swimming along a different path. \n\nWhile many studies have conside
 red static aspects of the flicking instability\, much remains unknown abou
 t its dynamics. It has been hypothesised that the hook eventually unbuckle
 s because it stiffens under the twist applied by the motor\, though the ti
 mescale of the flicking is much slower than what would be expected based o
 n this mechanism alone. I will present a reduced mathematical model for th
 e flicking instability\, which aims to elucidate the key features of its d
 ynamics. In particular\, the model explains what limits how quickly cells 
 can regain their maximum swimming speed once the motor reverses direction\
 , which in turn controls how efficiently bacteria may explore their enviro
 nment by flicking.\n\n\n
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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