Kapitel 17 Flashcards
Thin - flexible protein filament made from a chain of globular actin molecules; a major constituent of all eukaryotic cells - this cytoskeletal element is essential for cell movement and for the contraction of muscle cells.
actin filament
Protein that interacts with actin monomers or filaments to control the assembly - structure - and behavior of actin filaments and networks.
actin-binding protein
Specialized layer of cytoplasm on the inner face of the plasma membrane. In animal cells - it is rich in the actin filaments that govern cell shape and drive cell movement.
cell cortex
Cylindrical array of microtubules usually found in pairs at the center of a centrosome in animal cells. Also found at the base of cilia and flagella - where they are called basal bodies.
centriole
Microtubule-organizing center that sits near the nucleus in an animal cell; during the cell cycle - this structure duplicates to form the two poles of the mitotic spindle.
centrosome
Hairlike structure made of microtubules found on the surface of many eukaryotic cells; when present in large numbers - its rhythmic beating can drive the movement of fluid over the cell surface - as in the epithelium of the lungs.
cilium (plural cilia)
The rapid switching between growth and shrinkage shown by microtubules.
dynamic instability
Motor protein that uses the energy of ATP hydrolysis to move toward the minus end of a microtubule. One form of the protein is responsible for the bending of cilia.
dynein
Long - thin - actin-containing extension on the surface of an animal cell. Sometimes has an exploratory function - as in a growth cone.
filopodium (plural filopodia)
Long - whiplike structure capable of propelling a cell through a fluid medium with its rhythmic beating. Eukaryotic flagella are longer versions of cilia; bacterial flagella are completely different - being smaller and simpler in construction.
flagellum (plural flagella)
Fibrous cytoskeletal element - about 10 nm in diameter - that forms ropelike networks in animal cells; helps cells resist tension applied from outside.
intermediate filament
Class of intermediate filament abundant in epithelial cells - where it provides tensile strength; main structural component of hair - feathers - and claws.
keratin filament
A large family of motor proteins that uses the energy of ATP hydrolysis to move toward the plus end of a microtubule.
kinesin
Dynamic sheetlike extension on the surface of an animal cell - especially one migrating over a surface.
lamellipodium (plural lamellipodia)
Long - stiff - cylindrical structure composed of the protein tubulin. Used by eukaryotic cells to organize their cytoplasm and guide the intracellular transport of macromolecules and organelles.
microtubule
Accessory protein that binds to microtubules; can stabilize microtubule filaments - link them to other cell structures - or transport various components along their length.
microtubule-associated protein
Long - cylindrical structure that constitutes the contractile element of a muscle cell; constructed of arrays of highly organized bundles of actin - myosin - and other accessory proteins.
myofibril
Type of motor protein that uses ATP to drive movements along actin filaments. One subtype interacts with actin to form the thick contractile bundles of skeletal muscle.
myosin
Polymer composed of interacting molecules of myosin-II; interaction with actin promotes contraction in muscle and nonmuscle cells.
myosin filament
Simplest type of myosin - present in all cells; consists of a single actin-binding head and a tail that can attach to other molecules or organelles.
myosin-I
Type of myosin that exists as a dimer with two actin-binding heads and a coiled-coil tail; can associate to form long myosin filaments.
myosin-II
Fibrous layer on the inner surface of the inner nuclear membrane formed as a network of intermediate filaments made from nuclear lamins.
nuclear lamina
An inherent asymmetry that allows one end of an object to be distinguished from another; can refer to a molecule - a polymer (such as an actin filament) - or even a cell (for example - an epithelial cell that lines the mammalian small intestine).
polarity
Family of small - monomeric GTPases that controls the organization of the actin cytoskeleton.
Rho protein family
Highly organized assembly of actin and myosin filaments that serves as the contractile unit of a myofibril in a muscle cell.
sarcomere
See centriole
basal body
Active movement of a cell from one location to another.
cell locomotion
