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Biology Exam 2 > Cytoskeleton I > Flashcards

Cytoskeleton I Flashcards

1
Q

cytoskeleton is responsible for what type of mvt important to 2 cell types discussed in lecture

A

crawling

fibroblasts and white blood cells

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2
Q

describe the significance of RBC shape

A

cytoskeleton is responsible for maintaining their biconcave structure, imperative for protecting them against mechanical stress

mutations = anemia

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3
Q

cytoskeleton filaments are made up of?

A

several protofilaments made up of protein subunits

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4
Q

thermally unstable

A

a single protofilament

only requires 1 bond breakage

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5
Q

thermally stable

A

several protofilaments with lateral noncovalent links

requires the breakage of 3 bonds to remove 1 subunit

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6
Q

list the families of cytoskeleton filaments

A
  1. actin filaments – beads
  2. microtubules – slinky
  3. intermediate filaments – girders
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7
Q

general structure of actin filaments

A

2 stranded right handed helical polymer of actin monomers

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8
Q

functions of actin filaments

A
  1. cell surface shape
  2. whole cell locomotion, secretion, endocytosis
  3. contractile ring in mitosis
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9
Q

list the diameters of cytoskeleton filaments

A

actin - 5-9nm

microtubules - 25/14

intermediate - 10

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10
Q

arrangement of actin monomers

A

head to tail

structural polarity

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11
Q

differentiate between the ends of actin filaments

A

plus end = fast growing/shrinking

minus end = slow end

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12
Q

gross structure of microtubules

A

long hollow spiral cylinder of alpha and beta subunits

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13
Q

centrosome

A

all microtubules emanate from a central microtubule organization center

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14
Q

actin is flexible where microtubules are ____ and intermediate filaments are ____.

A

more rigid

strength

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15
Q

functions of microtubules

A
  1. position organelles
  2. intracellular transport
  3. separate chromosomes
  4. divide the cell
  5. centrioles and mitotic spindles
  6. flagella and cilia for sperm and eggs
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16
Q

microtubule protofilaments

A

hetero-dimer and alpha and beta subunits
via non-covalent bonds

a single strand

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17
Q

microtubule is = ?

A

13 protofilaments arranged in a hollow cylinder

making structure stiff and hard to bend

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18
Q

Tubulin-GTP conformation

A

straight stiff protofilaments

19
Q

Tubulin-GDP conformation

A

GTP cap lost
protofilaments curve
prone to depolymerization

20
Q

what is nucleoside hydrolysis?

A

the hydrolysis of bonded ATP/GTP to ADP/GDP on actin and microtubules

21
Q

subunits of intermediate filaments

A

elongated fibrous protein

central helical region

22
Q

list the progression of intermediate subunits to filaments

A
  1. subunit
  2. coiled dimer
  3. staggered tetramer = protofilament
  4. IF = 8 protofilaments
23
Q

staggered side to side arrangement of coiled dimers allows?

A

allows for bending and stretching of intermediate filaments

24
Q

what is the strongest cytoskeleton filament?

A

intermediate filaments

25
Q

functions of intermediate filaments

A
  1. mechanical strength
  2. resist mechanical stress
  3. formation of hair and nails
  4. strengthen CAMs
26
Q

2 monomers of intermediate filaments

A

coil/spiral about each other to form a coiled dimer

27
Q

2 dimers of an intermediate filament

A

arrange in staggered antiparallel arrangement = a staggered tetramer

28
Q

arrangement of terminals in a staggered tetramer

A

N to C
and
C to N

29
Q

___ number of protofilaments to create an intermediate filament

A

8 protofilaments = 8 tetramers

30
Q

which cytoskeleton filaments does not bind to triphosphates?

A

intermediate filaments

31
Q

example of intermediate filaments

A

keratins

32
Q

example of apical projections made of actin

A

microvilli

important for intestinal cells to 4x increase absorption

33
Q

basolateral domains of intestinal cells

A

transfer nutrients to blood stream

34
Q

desmosomes and hemidesmosomes

A

basolateral CAM junctions supported by intermediate filaments

35
Q

what is nucleation?

A

in order for filaments to form, subunits must first assemble into an aggregate/nucleus

36
Q

actin nucleation

A

the random collision of 3 monomers

37
Q

phases of growth

A
  1. nucleation
  2. elongation
  3. steady state
38
Q

T form

A

actin or microtubules bound to ATP/GTP

39
Q

D form

A

actin or microtubules bound to ADP/GDP

40
Q

describe treadmilling of _____

A

actin
constant addition at plus end = rate of depolymerization
equilibrium
polymer length constant

41
Q

define catastrophe and actin

A

rapid conversions
C - from normal growth to rapid loss

R - from rapid loss to normal addition

42
Q

describe the dynamic instability, predominating in ____

A

microtubules
loss of GTP cap, causing a conformational change into curved protofilaments
resulting in prone/easily removed subunits

progressive disruption/dissociation

43
Q

dynamic instability is imperative to?

A

how microtubules separate chromosomes in division

44
Q

motor proteins are responsible for?

A
  1. move organelles
  2. move the filament itself
  3. transport vesicles

Biology Exam 2 (9 decks)

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