The Cytoskeleton Flashcards
(143 cards)
1
Q
The cytoskeleton is also called the
A
the skeleton of our cells
2
Q
3 components of the cytoskeleton
A
intermediate filaments, microtubules, and actin filaments
3
Q
what is the location of intermediate filaments
A
area where cells come in contact with one another
4
Q
what do intermediate filaments help with?
A
anchoring the cells with cell junction
5
Q
where do microtubules start and go out too?
A
start in the nucleus and go out to the cell membrane
6
Q
where do actin filaments lie
A
beneath the plasma membrane and help with cell shape
7
Q
what helps with providing strength to axons and gives meshwork inside the nucleus giving shape and structure
A
intermediate filaments
8
Q
whats in the middle of microtubules and actin filaments
A
intermediate filaments
9
Q
where are intermediate filaments more prominent
A
neurons
10
Q
can motor proteins figure out direction with intermediate filaments
A
no they can not
11
Q
in intermediate filaments, the alpha helix wraps around one another to form a
A
coil coil dimer
12
Q
is there polarity in the structure of intermediate filaments
A
yes
13
Q
when do you lose polarity in an intermediate filament
A
tetramer
14
Q
how do motor proteins know where to go
A
they look for polarity
15
Q
are intermediate filaments hard or easy to break down
A
they are very hard to break down
16
Q
how many tetramers do you put together to form the intermediate filaments
A
8 tetramers
17
Q
definition for a molecule cannot be broken by the energy of the environment
A
thermal stability
18
Q
how must intermediate filaments be disassembled
A
with cellular machinery
19
Q
neurofilaments are composed of
A
intermediate filaments
20
Q
what are essential for growth and stability of neurons
A
neurofilaments
21
Q
what intermediate filaments is abundant in hair and nails
A
keratin
22
Q
a genetic skin disorder from mutations in keratin is called
A
epidermolysis bullosa simplex
23
Q
what share structural similarities
A
microtubules and actin
24
Q
are noncovalent bonds strong or weak
A
weak
25
microtubules are composed of
tubulin protein monomers
26
actin filaments are composed of
G-actin protein monomers
27
single protofilaments are
thermally unstable
28
where are multiple protofilaments assembled and disassembled usually
at the ends
29
microtubules originate from
MTOC
30
MTOCs are also called
centrosomes
31
microtubules are crucial for
cell division
32
what look like long straight cylinders / drinking straws
microtubules
33
the tubulin monomer protein is composed of an
alpha-beta heterodimer
34
how does a microtubule assemble
alpha beta alpha beta
35
what are the ends of the microtubules called
beta and alpha tubulin
36
the beta end of a microtubule can bind and hydrolyze
GTP
37
is beta tubulin a slow or fast hydrolyzer
slow
38
where is GTP stuck in the microtubule
alpha end
39
can GTP be hydrolyzed in the alpha end of a microtubule
no it is stuck
40
how many protofilaments does it take to form a hollow straw
13
41
alpha and beta contacts in what
heterodimer and filament
42
any changes that need to happen in a microtubule occur where
one end or the other
43
microtubule filaments are nucleated from the
centrosome
44
motor protein in the MTOC can sense alpha and beta which tell it if it is going
inside or outside
45
what is around the pair of centrioles
pericentriolar
46
what are microtubules growing from gamma tubulin ring complexes of the centrosome called
y-TuRC
47
what side are the MTOCs at
minus side
48
what side are the TuRC at
plus ends
49
in the MTOC do the negative or positive sides face out
the plus ends face out
50
is GTP- tubulin or GDP-tubulin more stable
GTP-tubulin
51
where is majority of microtubule growth
the plus end
52
the plus end of microtubules are fast which means
hydrolysis lags behind
53
most of the minus ends are held at the? which mean
MTOCS, no growth or loss
54
whenever we add tubulin to a microtubule its in its
GTP bound form
55
is t-tubulin being added to both sides of the microtubule
yes, but falls off the minus end as fast as it is added
56
why does the t-tubulin fall off the minus end so fast
is it hydrolyzed right away to d-tubulin
57
growth to shrinkage is called
castastrophe
58
shrinkage to growth is called
rescue
59
growing is when
addition of GTP tubulin outpaces hydrolysis
60
shrinkage is when
hydrolysis has outpaced addition
61
if the t-tublin addition to the plus end slows, then
GTP cap gets hydrolyzed
62
does shrinking and growing happen together or independently
independently
63
what bundles filaments into higher-order structures by stabilizing and cross-linking
MAPs
64
what protein binds to the microtubule to help prevent it from being broken down
tau
65
what are some linkage points between microtubules and cancer
cell division, microtubules is what pools apart the sister chromatids, and improper sister chromatid separation can lead to cancer
66
what is the smallest of the cytoskeleton elements
actin
67
actin forms a helical polymer how many nm in diameter
8 nm
68
what is a main component of actin
muscle contraction
69
actin is also called
microfilaments
70
what does actin bind too
ATP
71
what does tubulin bind to
GTP
72
actin can hydrolyze ATP to
ADP
73
is there a plus and minus end in actin
yes
74
is actin a slow or fast ATPase
slow
75
growth is mainly at what end of actin
the plus end
76
actin polymers filaments are nucleated by
ARP2/3 complex
77
where does ARP2/3 bind
the minus end
78
what does ARP2/3 do
binds to minus end and facilitates growth outward from the plus end
79
the ARP is usually at the
cell periphery
80
ARP2/3 arranges into what upon activation
scaffold
81
where is gamma turc usually
at the nucleus
82
does gamma turc or arp facilitate branching
arp
83
how many filaments can ARP2/3 complex bind to
2 at once
84
actin filament end can be
capped for stability
85
what is happening in listeriosis
an intracellular parasite hijacks ARP2/3 and uses actin like a rocket
86
what has loose packing which allows myosin II to enter the bundle
contractile bundle
87
what consists of a contractile bundle
actin filaments and alpha actinin
88
what bundle packs much tighter and prevents myosin II from binding
parallel bundle
89
what consists of a parallel bundle
actin filaments and fimbrin
90
what is fimbrin
smaller alpha actinin that results in tighter packing of actin
91
actin bundles give cells their
shape
92
what do intermediate filaments anchor the cells to
gut epithethial cells
93
what determines and maintains the polarity of a cell
cytoskeleton
94
what forms contractile rings and pinches two daughter cells in distinct units
actin
95
a mutation in smooth muscle cell actin correlates with higher instances of premature onset of
coronary artery disease and premature ischemic strokes
96
Fluid shear stress plays an essential role in
maintaining vascular homeostasis
97
laminar blood flow with higher FFS means
atheroprotective areas
98
turbulent blood flow with low FSS means
atheroprone areas
99
what do motor proteins look for on a cytoskeleton element
polarity
100
does actin respond to inflammatory stress
yes
101
microtubule motor proteins are
kinesin and dynein
102
actin motor proteins are
myosin
103
what side does kinsein walk towards
plus end
104
what side are motor domains on kinesin
n terminus
105
what side are cargo domains on kinesin
c terminus
106
what side of kinesin does cargo bind
c terminus
107
multiple rounds of ATP hydrolysis allow cyclical binding and release of the
kinesin heads
108
does kinesin walkins consume a lot of atp
yes
109
kinesin requires what pathway and what coat proteins
exocytic pathway and COPII coats
110
what do dyneins require
accessory proteins to binds to its cargo
111
what direction are dyneins going in
the minus side
112
what does dynactin use to bind to the vesicle
dynactin complex
113
what pathways would dynein use
endocytosis, clathrin and retrieval
114
what does nocodazole do
depolymerizes microtubules
115
where does myosin move towards
the minus end
116
does myosin walk
no it is more like a power stroke
117
what does myosin use to facilitate myosin heads binding to actin to push along the actin filament
ATP binding hydrolysis
118
skeletal muscles are bundles of
muscle fibers
119
how are muscle fibers formed
by fusion of many individual cells during development
120
what are thin filaments in myofibril structure
actin
121
what are thick filaments in myofibril structure
myosin
122
sarcomeres are
one z disc to another
123
what causes muscle contraction? when comes together or goes apart
comes together
124
what prevents myosin from binding
tropomyosin
125
what happens which exposes myosin binding
Ca
126
myosin permits
cell movement
127
cells are able to crawl along a substrate by using a
four-wheel drive type mechanism
128
what do we rely on when we want to push the plasma membrane forward
ARP2/3 because it provides branching
129
true or false: anything that happens in the cytoplasms is indirectly connected to the nucleus
true
129
what proteins do we use for indirect coupling
Kash and SUN
130
cells are indirectly couples across their
cell-cell junctions
131
what can we target in order to target cancer
microtubules
132
what is a very common chemotherapy medication which prevents microtubule disassembly, thereby killing rapidly dividng cells
taxol
133
what stabilizes MTS and prevents cell division
taxol
134
what sends a signal
action potential
135
what is the source of depolarization
the opening of ion channels
136
order of a nerve stimulus
closed, open, inactivated, closed
137
what happens during synapse for action potential
where we convert the electrical signal into a chemical signal and back to an electrical signal
138
what is rapidly removed from cleft after activation of post-synaptic cell
neurotransmitter
139
what causes muscle contraction
release of calcium
140
muscle contraction is active or passive
passive process
141
what has a low concentration of ca2+ when muscle is releaxed and a high concentration when contracted
sarcoplasm
142
ATP hydrolysis changed the conformation of the calcium pump, allowing it to move calcium ions from
sarcoplasm into sarcoplasmic reticulum
