Ch 17 - Cytoskeleton

Question 1

actin filament

Answer 1

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

Question 2

actin-binding protein

Answer 2

protein that interacts with actin monomers or filaments to control the assembly, structure and behaviour of actin filaments and networks

Question 3

cell cortex

Answer 3

specialized layer of cytoplasm on the inner face of the plasma membrane. in animal cells, it is rich in actin filaments that govern cell shape and drive cell movement

Question 4

centriole

Answer 4

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

Question 5

centrosome

Answer 5

specialized DNA sequence that allows duplicated chromosomes to be separated during M phase; can be seen as the constricted region of a mitotic chromosome

Question 6

cilium

Answer 6

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

Question 7

cytoskeleton

Answer 7

system of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell shape and the capacity for directed movement. its most abundant components are actin filaments, microtubules and intermediate filaments

Question 8

dynamic instability

Answer 8

the rapid switching between growth and shrinkage shown by microtubules

Question 9

dynein

Answer 9

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

Question 10

filopodium

Answer 10

long, thin, actin-containing extension on the surface of an animal cell. sometimes has an exploratory function, as in a growth cone

Question 11

flagellum

Answer 11

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

Question 12

intermediate filament

Answer 12

fibrous cytoskeletal element, about 10nm in diameter, that forms ropelike networks in animal cells; helps cells resist tension applied from outside

Question 13

keratin filament

Answer 13

class of intermediate filament abundant in epithelial cells, where it provides tensile strength; main structural component of hair, feathers and claws

Question 14

kinesin

Answer 14

a large family of motor proteins that uses the energy of ATP hydrolysis to move toward the plus end of a microtubule

Question 15

lamellipodium

Answer 15

dynamic sheetlike extension on the surface of an animal cell, especially one migrating over a surface

Question 16

microtubule

Answer 16

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

Question 17

microtubule-associated protein

Answer 17

accessory protein that binds to microtubules; can stabilize microtubule filaments, link them to other cell structures or transport various components along their length

Question 18

motor protein

Answer 18

protein such as myosin or kinesin that uses energy derived from the hydrolysis of a tightly bound ATP molecule to propel itself along a protein filament or polymeric molecule

Question 19

myofibril

Answer 19

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

Question 20

myosin

Answer 20

type of motor protein that uses ATP to drive movements along actin filaments. one subtype interacts with actin to form the tick contractile bundles of skeletal muscle

Question 21

myosin filament

Answer 21

polymer composed of interacting molecules of myosin-II; interaction with actin promotes contraction in muscle and nonmuscle cells

Question 22

myosin-I

Answer 22

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

Question 23

myosin-II

Answer 23

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

Question 24

nuclear lamina

Answer 24

fibrous layer on the inner surface of the inner nuclear membrane formed as a network of intermediate filaments made from nuclear lamins

Question 25

polarity

Answer 25

an inherit asymmetry that allows one end of an object to be distinguished from another; can refer to a molecule, a polymer (such as actin filament) or even a cell (for example, an epithelial cell that lines the mammalian small intestine)

Question 26

Rho protein family

Answer 26

family of small, monomeric GTPases that controls the organization of the actin cytoskeleton

Question 27

sarcomere

Answer 27

highly organized assembly of actin and myosin filaments that serves as the contractile unit of a myofibril in a muscle cell

Question 28

tubulin

Answer 28

protein from which microtubules are made