chapter eighteen

Question 1

what are networks of protein filaments that extend through the cell, which organize, give shape and do work

Answer 1

cytoskeleton

Question 2

what are the three filament systems

Answer 2

intermediate, microtubules, and actin

Question 3

microtubules and actin are _____ and ______

Answer 3

dynamic, polarized

Question 4

this cytoskeleton system has great tensile strength, form network of filaments that surround nucleus and extend to plasma membrane

Answer 4

intermediate

Question 5

the ____ is the assembly subunit of the intermediate filament

Answer 5

tetramer

Question 6

keratin, nuerofilaments, nuclear lamins

Answer 6

intermediate filaments

Question 7

associates with the nuclear pore complex and chromatin

Answer 7

nuclear lamina (intermediate filaments)

Question 8

mutation in nuclear lamina, premature aging disease

Answer 8

progeria

Question 9

_____ are crucial for all eukaryotic cells, organize the organelles in the cytoplasm

Answer 9

microtubules

Question 10

______ for the mitotic spindle

Answer 10

microtubules

Question 11

_____ assemble into cillia and flagella, function depends on motor proteins

Answer 11

microtubules

Question 12

_____ assemble from alpha-beta tubulin dimers, 13 protofilaments (polarized structures)

Answer 12

microtubules

Question 13

microtubules: alpha is exposed at ____ end and beta is exposed at ____ end

Answer 13

minus, plus

Question 14

_____ are microtubules organizing centers

Answer 14

centrosomes

Question 15

a pair of _____ are within the centrosome

Answer 15

centrioles

Question 16

individual microtubules grow and shrink in a process called ____ _____

Answer 16

dynamic instability

Question 17

dynamic instability of microtubules is driven by ____ _____

Answer 17

GTP hydrolysis

Question 18

Tubulin binds ____ and after a time delay it hydrolyzes ____ to _____

Answer 18

GTP, GTP to GDP

Question 19

When GDP tubulin is produced, _____ are less stable; rapid, spontaneous _____ occurs

Answer 19

protofilaments, disassembly

Question 20

_____ is a plus end directed motor

Answer 20

kinesin

Question 21

_____ is a minus end directed motor

Answer 21

dynein

Question 22

____ _____ attach to vesicles and organelles and move these structures into the cell

Answer 22

motor proteins

Question 23

____ ____ is moved to the periphery by a plus end directed motor

Answer 23

endoplasmic reticulum

Question 24

___ _____ is moved to the cell interior by a minus end directed motor

Answer 24

golgi apparatus

Question 25

____ and _____ have stable microtubule core structures with dynein motor proteins which drive their movement

Answer 25

cillia and flagella

Question 26

cillia and flagella have a __ ___ structure

Answer 26

9+2

Question 27

____ linkages permit bending movements used in cilia and flagella

Answer 27

nexin

Question 28

____ filaments are organized into microvilli, stress fibers, filopodia, lamellipodia, and contractile rings

Answer 28

actin

Question 29

assembled from individual _____ monomers which are bound by ATP

Answer 29

actin filaments, actin

Question 30

_____ of actin is better on the plus end and _____ occurs more easily on the minus end

Answer 30

assembly, dissasembly

Question 31

cells extend protrusions (filopodia and lamellipodia) that are _____ structures, these protrusions attach to the surface

Answer 31

actin

Question 32

the cell pull its trailing edge with ______ contraction

Answer 32

myosin

Question 33

actin associates with _____ a motor protein that drives _____ dependent movements

Answer 33

myosin, ATP

Question 34

myosin __ assembles into bipolar filaments called myosin filaments

Answer 34

II

Question 35

______ filaments can slide actin filaments in opposite directions (muscle contraction)

Answer 35

bipolar

Question 36

___ ___ are multinucleate cells that are filled with myofibrils, which numerous sarcomeres

Answer 36

muscle fibers

Question 37

______ are arrangements of ____ filaments in the center, _____ filaments in the periphery

Answer 37

sarcomeres, thick, thin

Question 38

many repeating ______ make the myofibril

Answer 38

sarcomeres

Question 39

muscle contraction is caused by simultaneous shortening of the muscle cell's ________

Answer 39

sarcomeres

Question 40

filament sliding is mediated by ____ ______

Answer 40

myosin motors

Question 41

myosin binds ____, which is released by binding ATP

Answer 41

actin

Question 42

hydrolysis of _____ cocks the myosin head

Answer 42

ATP

Question 43

binding _____ causes phosphate release and the power stroke

Answer 43

actin

Question 44

______ influx after muscle depolarization after muscle depolarization causes contraction

Answer 44

calcium

Question 45

_______ calcium channels cause the sarcoplasmic reticulum calcium channels to open

Answer 45

T-Tubule

Question 46

calcium binds the ____ complex, which moves the associated protein and exposes the ____ binding site on _____ filaments

Answer 46

troponin, myosin, actin