Ch 17 - Cytoskeleton

Question 1

what is the function of the cytoskeleton?

Answer 1

provides support, structure, and movement

Question 2

what are intermediate filaments?

Answer 2

strong and rope like
strengthen cells against mechanical stress
support nuclear envelope

Question 3

what are intermediate filaments composed of?

Answer 3

fibrous proteins

ropelike fibers

Question 4

how do you tell the ends of intermediate filaments apart?

Answer 4

based on the proteins that bind to the ends

Question 5

Do intermediate filaments have polarity?

Answer 5

no

Question 6

what are desmosomes?

Answer 6

anchoring junctions
where cells connect
strengthen by intermediate filaments

Question 7

what are the types of intermediate filaments?

Answer 7

cytoplasmic and nuclear

Question 8

what are the cytoplasmic intermediate filaments?

Answer 8

keratin
vimentin & vimentin-related
neurofilaments

Question 9

what are the nuclear intermediate filaments?

Answer 9

nuclear lamins

Question 10

where are keratin intermediate filaments found?

Answer 10

epithelial cells

Question 11

where are vimentin & vimentin-related intermediate filaments found?

Answer 11

connective tissue, muscle cells, and glial cells

Question 12

where are nuclear lamins intermediate filaments found?

Answer 12

in all animal cells

Question 13

where are nerve cell intermediate filaments found?

Answer 13

neurofilaments

Question 14

how do proteins help filaments?

Answer 14

proteins help filaments bind, support, and transport things

Question 15

What is plectin?

Answer 15

protein that helps stabilize intermediate filaments

it helps intermediate filament anchor to microtubules

Question 16

what happens when there is a defect in plectin?

Answer 16

it can causes symptoms of: epidermolysis bullosa, muscular dystrophy, neurodegeneration

Question 17

what do nuclear lamins do for intermediate filaments?

Answer 17

phosphorylation regulates filaments

Question 18

what happens to intermediate filaments when nuclear lamins are phosphorylated?

Answer 18

destabilizing the structure

the phosphates start to loosen the lamin

Question 19

what happens to intermediate filaments when nuclear lamins are dephosphorylated?

Answer 19

reassembly for structure

no phosphates allow tighter formation of the lamin

Question 20

what causes progeria in terms of intermediate filaments?

Answer 20

defects in the nuclear lamin

Question 21

what are the symptoms of progeria?

Answer 21

premature aging

Question 22

what causes epidermolysis bullosa in terms of intermediate filaments?

Answer 22

mutation of keratin gene in plectin

Question 23

what are the symptoms of epidermolysis bullosa?

Answer 23

skin easily blisters and damages

Question 24

a defect in which type of intermediate filament would cause a phenotype in all tissue types?

Answer 24

nuclear lamins

Question 25

what are microtubules?

Answer 25

hollow tubes with distinct ends | provides centrosome and cell interior organization

Question 26

____ drive intracellular transport

Answer 26

motor proteins

Question 27

what are microtubules composed of?

Answer 27

tubulin | alpha and beta subunits

Question 28

how do microtubules grow?

Answer 28

alpha units are added to the plus end (alpha)

Question 29

how do microtubules disassemble?

Answer 29

remove beta subunits from the minus end (beta end)

Question 30

Do microtubules have polarity?

Answer 30

yes

Question 31

what are microtubules anchored to?

Answer 31

centrosomes

Question 32

what do centrosomes control in terms of microtubules?

Answer 32

length, number, and orientation

Question 33

what is found on the surface of the centrosome?

Answer 33

gamma tubulin rings

Question 34

what does gamma tubulin do?

Answer 34

it directly binds to microtubule and allows growth

Question 35

what is dynamic instability?

Answer 35

microtubules grow and shrink very rapidly from one end

Question 36

what controls dynamic instability?

Answer 36

GTP hydrolysis

Question 37

what happens to a GTP associated tubulin?

Answer 37

it elongates

Question 38

what happens to a GDP associated tubulin?

Answer 38

it disassembles

Question 39

what does capping of microtubules do?

Answer 39

prevents disassembly

Question 40

what does taxol do to microtubules?

Answer 40

binds to microtubules, prevents disassembly

Question 41

what does colchicine do to microtubules?

Answer 41

binds free tubulin, prevents polymerization (growth)

Question 42

what do drugs that prevent normal microtubules turnover do?

Answer 42

they inhibit mitosis | anti-cancer drugs

Question 43

which cell would have the longest microtubules?

Answer 43

one treated with taxol | prevents disassembly

Question 44

what do microtubule motor proteins rely on?

Answer 44

ATP hydrolysis

Question 45

what are the microtubule motor proteins?

Answer 45

kinesins and dyneins

Question 46

what do kinesins do?

Answer 46

microtubule motor proteins that move towards the plus end (away from the cell body)

Question 47

what do dyneins do?

Answer 47

microtubule motor proteins that move towards the minus end (towards the cell body)

Question 48

how do nerve cells use microtubules?

Answer 48

as railroad tracks for motor proteins

Question 49

what is the "9+2" arrangement?

Answer 49

2 microtubules in the center 9 pairs of microtubules around the center microtubules creates cilia and flagella

Question 50

what does ciliary dynein do?

Answer 50

generate movement

Question 51

what is the difference between cilia and flagella?

Answer 51

Cilia are shorter and more numerous. Flagella are longer and fewer on cells.

Question 52

what can mutations in ciliary dynein cause?

Answer 52

male infertility | mucus

Question 53

what happens to cilia when there is a mutation in ciliary dynein?

Answer 53

they have normal shape and structure but abnormal movement because there is a mutation in motor proteins

Question 54

What are actin filaments?

Answer 54

thin and flexible filaments | occur in bundles

Question 55

what do actin filaments do?

Answer 55

support the plasma membrane

Question 56

what are actin filaments responsible for?

Answer 56

membrane crawling

Question 57

what does it mean that actin filaments are dynamic?

Answer 57

they have rapid restructuring

Question 58

what does the rapid rearrangement of actin filaments depend on?

Answer 58

the proteins interacting with it

Question 59

what do actin/myosin do?

Answer 59

help form the contractile ring

Question 60

what type of hydrolysis does actin depend on?

Answer 60

ATP hydrolysis

Question 61

what is the orientation of actin filaments?

Answer 61

plus end | minus end

Question 62

what end does actin filaments grow from?

Answer 62

plus end

Question 63

what end do actin filaments dissemble from?

Answer 63

minus end

Question 64

Do actin filaments have polarity?

Answer 64

yes

Question 65

what does it mean that actin treadmill?

Answer 65

they grow from one end and shrink from the other

Question 66

how does actin grow and shrink?

Answer 66

they grow from one end and shrink from the other

Question 67

what is the difference between treadmilling and dynamic instability?

Answer 67

treadmilling - movement of monomers through filament; uses ATP hydrolysis; actin dynamic instability - growth and disassembly from one end; GTP hydrolysis; microtubules

Question 68

what do actin binding proteins do?

Answer 68

help cell control if actin is protruding from plasma membrane or shrinking

Question 69

what does phalloidin do to actin filaments?

Answer 69

binds and stabilizes filaments

Question 70

what does cytochalasin do to actin filaments?

Answer 70

caps actin filament plus ends, preventing polymerization (growth)

Question 71

what does latrunculin do to actin filaments?

Answer 71

binds to actin monomers and prevents their polymerization

Question 72

which of the actin drugs would cause actin filaments to elongate?

Answer 72

phalloidin; stabilizes the filament allowing growth

Question 73

how do actin filaments promote cell crawling?

Answer 73

they extend lamellipodia they contract the distal end and they form attachments to the substratum

Question 74

what must happen to extend lamellipodia?

Answer 74

actin polymerization and contraction

Question 75

what does the contraction of actin depend on?

Answer 75

actin/myosin

Question 76

in cell crawling, what does actin polymerization do?

Answer 76

pushes leading edge forward with ARPs and formins

Question 77

what does a capping protein do on actin filaments?

Answer 77

stop growth

Question 78

what does the motor protein myosin do with actin filaments?

Answer 78

hydrolyze ATP | move towards plus end of actin filament

Question 79

where is type I myosin found?

Answer 79

all cells

Question 80

where is type II myosin found?

Answer 80

muscle cells

Question 81

what do Rho proteins do in actin filaments?

Answer 81

control various processes (cytoskeletal reorganization

Question 82

what activates Rho proteins in actin filaments?

Answer 82

extracellular signals

Question 83

what helps Rho proteins in cytoskeletal reorganization?

Answer 83

monomeric GTPases

Question 84

in general, what causes muscle contraction?

Answer 84

interactions between actin and myosin | actin slides against myosin

Question 85

what triggers muscle contraction in muscle tissues?

Answer 85

cytosolic increase in Ca2+

Question 86

what are the types of muscle cells?

Answer 86

skeletal cardiac smooth

Question 87

which muscle cells has voluntary contraction?

Answer 87

skeletal

Question 88

what muscle cells have involuntary contraction?

Answer 88

cardiac and smooth

Question 89

what is myosin II?

Answer 89

a dimer of two inter-twined myosin subunits | it has a globular ATPase head with coiled tail

Question 90

what happens to the head of Myosin II during ATPase activity?

Answer 90

it goes through a conformational change during ATP hyrdolysis

Question 91

what happens as myosin contracts?

Answer 91

actin slides toward each other

Question 92

what are myofibrils composed of?

Answer 92

sarcomeres

Question 93

what do z disks do?

Answer 93

they anchor actin and myosin filaments

Question 94

what is a sarcomere?

Answer 94

contractile unit of muscle cells

Question 95

where is the actin found in sarcomeres?

Answer 95

thin filaments

Question 96

where is the myosin found in sarcomeres?

Answer 96

thick filaments

Question 97

how does muscle contraction occur?

Answer 97

1. an increase in cytosolic Ca2+ binds to troponin 2. moves tropomyosin 3. reveals myosin binding site 4. myosin hydrolyzes ATP 5. actin and myosin bind 6. muscle contracts

Question 98

what does myosin movement depend on?

Answer 98

ATP hydrolysis

Question 99

you give a medication that prevents the reabsorption of calcium by sarcoplasmic reticulum. What would be the expected effect of this treatment on a contracting muscle?

Answer 99

continual muscle contraction. | Muscle cannot relax

Question 100

Use the image of a sarcomere to answer the following question. Which letter is labeling the Z disc?

Answer 100

c

Question 101

Use the image of a sarcomere to answer the following question. Which letter is labeling the myosin?

Answer 101

B

Question 102

Use the image of a sarcomere to answer the following question. Which letter indicates where actin filaments can be found?

Answer 102

A

Question 103

where are intermediate filaments found?

Answer 103

extending from a ring surrounding the nucleus to the plasma membrane

Question 104

where are microtubules found?

Answer 104

the centrosome, adjacent to the nucleus

Question 105

where are actin filaments found?

Answer 105

cell cortex, microvilli, near the outside of the cell/plasma membrane