chapter eighteen Flashcards

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1
Q

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

A

cytoskeleton

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2
Q

what are the three filament systems

A

intermediate, microtubules, and actin

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3
Q

microtubules and actin are _____ and ______

A

dynamic, polarized

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4
Q

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

A

intermediate

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5
Q

the ____ is the assembly subunit of the intermediate filament

A

tetramer

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6
Q

keratin, nuerofilaments, nuclear lamins

A

intermediate filaments

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7
Q

associates with the nuclear pore complex and chromatin

A

nuclear lamina (intermediate filaments)

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8
Q

mutation in nuclear lamina, premature aging disease

A

progeria

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9
Q

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

A

microtubules

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10
Q

______ for the mitotic spindle

A

microtubules

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11
Q

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

A

microtubules

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12
Q

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

A

microtubules

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13
Q

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

A

minus, plus

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14
Q

_____ are microtubules organizing centers

A

centrosomes

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15
Q

a pair of _____ are within the centrosome

A

centrioles

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16
Q

individual microtubules grow and shrink in a process called ____ _____

A

dynamic instability

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17
Q

dynamic instability of microtubules is driven by ____ _____

A

GTP hydrolysis

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18
Q

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

A

GTP, GTP to GDP

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19
Q

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

A

protofilaments, disassembly

20
Q

_____ is a plus end directed motor

A

kinesin

21
Q

_____ is a minus end directed motor

A

dynein

22
Q

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

A

motor proteins

23
Q

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

A

endoplasmic reticulum

24
Q

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

A

golgi apparatus

25
Q

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

A

cillia and flagella

26
Q

cillia and flagella have a __ ___ structure

A

9+2

27
Q

____ linkages permit bending movements used in cilia and flagella

A

nexin

28
Q

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

A

actin

29
Q

assembled from individual _____ monomers which are bound by ATP

A

actin filaments, actin

30
Q

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

A

assembly, dissasembly

31
Q

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

A

actin

32
Q

the cell pull its trailing edge with ______ contraction

A

myosin

33
Q

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

A

myosin, ATP

34
Q

myosin __ assembles into bipolar filaments called myosin filaments

A

II

35
Q

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

A

bipolar

36
Q

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

A

muscle fibers

37
Q

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

A

sarcomeres, thick, thin

38
Q

many repeating ______ make the myofibril

A

sarcomeres

39
Q

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

A

sarcomeres

40
Q

filament sliding is mediated by ____ ______

A

myosin motors

41
Q

myosin binds ____, which is released by binding ATP

A

actin

42
Q

hydrolysis of _____ cocks the myosin head

A

ATP

43
Q

binding _____ causes phosphate release and the power stroke

A

actin

44
Q

______ influx after muscle depolarization after muscle depolarization causes contraction

A

calcium

45
Q

_______ calcium channels cause the sarcoplasmic reticulum calcium channels to open

A

T-Tubule

46
Q

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

A

troponin, myosin, actin