Cell Motility

(Movie of a Crawling Neutrophil Chasing a Bacterium; Description by Tom Stossel)

Mainly due to their small size, cell's operate at low Reynold's number, where inertial effects are negligble.

Many cells move, using forces generated by polymerization of cytoskeloton filaments (such as actin)

"Tour on Video Microscopy" from the Institute of Molecular Biology, Austrian Academy of Sciences (offline)
Steady state of actin involves treadmilling of monomers by polymerization and depolymerization.
Actin-based motility (from the Theriot Lab) (offline)
- In vivo- the pathogen Lysteria
  
  Listeria monocytogenes in GFP-actin-transfected MDCK cells generously provided by Angela Barth.

In vitro- spherical latex beads coated with protein ActA in solution of Actin and ATP