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Motility is a biological term which refers to the ability to move spontaneously and actively, consuming energy in the process. Most animals are motile but the term applies to single-celled and simple multicellular organisms, as well as to some mechanisms of fluid flow in multicellular organs, in addition to animal locomotion. Motile marine animals are commonly called free-swimming.

The opposite of motility is sessility.

Motility may also refer to an organism's ability to move food through its digestive tract, i.e., peristaltics (gut motility, intestinal motility, etc.).^[1]

Cellular-level motility[link]

At the cellular level, undulipodia (singular undulipodium) are slender cellular protuberances that project from the much larger cell body. Undulipodia, which consists of both eukaryotic flagella and eukaryotic cilia,^[2] may be motile or non-motile. Both motile cilia and flagella are motile. Primary cilia typically serve as sensory cellular organelles, and are non-motile. Eukaryotic cilia are structurally identical to eukaryotic flagella, although distinctions are sometimes made according to function and/or length.^[3]

Examples of single-cellular motility[link]

• Sperm cells, propelled by the regular beat of their flagellum.
• The bacterium E. coli, which swims by rotating a helical prokaryotic flagellum.
• Non-motile examples includes Yersinia pestis @37 degrees C, Klebsiella pneumoniae, & Shigella.

Movements[link]

Movements^{[clarification needed]} can be:

• along a chemical gradient (see chemotaxis)
• along a temperature gradient (see thermotaxis)
• along a light gradient (see phototaxis)
• along a magnetic field line (see magnetotaxis)
• along an electric field (see galvanotaxis)
• along the direction of the gravitational force (see gravitaxis)
• along a rigidity gradient (see durotaxis)
• along a gradient of cell adhesion sites (see haptotaxis)
• along other cells or biopolymers

See also[link]

• Cell migration

References[link]

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Julie A. Theriot (born 1967) is an American microbiologist, professor at the Stanford University School of Medicine,^[1] and Theriot Lab.^[2] She was a Predoctoral Fellow, and Investigator at the Howard Hughes Medical Institute.^[3] She was a fellow at the Whitehead Institute for Biomedical Research.^[4]

She graduated from the Massachusetts Institute of Technology with a B.S. in Biology and Physics in 1988, and from the University of California, San Francisco, with a Ph.D. in Cell Biology in 1993. Her work has investigated bacterial infections, such as Shigella, and Listeria.^[5]

Awards[link]

• 2004 MacArthur Fellows Program

Works[link]

• "Mechanism for cell shapeliness decoded from fish scales", Nature 453, xi (22 May 2008) ^[6]

• Physical biology of the cell, Authors Rob Phillips, Janè Kondev, Julie Theriot, Garland Science, 2008, ISBN 978-0-8153-4163-5
• "Bacterial Manipulation of the Host Cell Cytoskeleton", Cellular microbiology, Editor Pascale Cossart, ASM Press, 2005, ISBN 978-1-55581-302-4
• "Movement of Bacterial Pathogens Driven by Actin Polymerization", Motion analysis of living cells, Editors David R. Soll, Deborah Wessels, Wiley-IEEE, 1998, ISBN 978-0-471-15915-5

References[link]

External links[link]