Concept 4.6: The cytoskeleton is a network of fibers that organizes structures and activities in the cell

microfilament

A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up part of the cytoskeleton and acting alone or with myosin to cause cell contraction; also known as actin filament.

intermediate filament

A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments.

basal body

A eukaryotic cell structure consisting of a "9 + 0" arrangement of microtubule triplets. The basal body may organize the microtubule assembly of a cilium or flagellum and is structurally very similar to a centriole.

actin

A globular protein that links into chains, two of which twist helically about each other, forming micrfilaments (actin filaments) in muscle and other kinds of cells.

microtubule

A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella.

flagellum (plural, flagella)

A long cellular appendage specialized for locomotion. Like motile cilia, eukaryotic flagella have a core with nine outer doublet microtubules and two inner single microtubules (the "9 + 2" arrangement) ensheathed in an extension of the plasma membrane. Prokaryotic flagella have a different structure.

cytoskeleton

A network of microtububules, microfilaments, and intermediate filaments that extends throughout the cytoplasm and serves a variety of mechanical, transport, and signaling functions.

motor protein

A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell.

cilium (plural, cilia)

A short appendage containing microtubules in eukaryotic cells. A motile cilium is specialized for locomotion or moving fluid past the cell; it is formed from a core of nine outer doublet microtubules (the "9 + 2" arrangement) ensheathed in an extension of the plasma membrane. A primary cilium is usually nonmotile and plays a sensory and signaling role; it lacks the two inner microtubules (the "9 + 0" arrangement)

centriole

A structure in the centrosome of an animal composed of a cylinder of microtubule triplets arranged in a 9 + 0 pattern. A centrosome has a pair of centrioles.

centrosome

A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. A centrosome has two centrioles.

myosin

A type of motor protein that associates into filaments that interact with actin filaments, causing cell contraction.

dynein

In cilia and flagella, a large motor protein extending from one microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in dynein shape that lead to bending of cilia and flagella.