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Cell Bio > Exam 2 - mod 6 > Flashcards

Exam 2 - mod 6 Flashcards

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1
Q

organelles are angchored

A

translocated along diff filament structure sin cells

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2
Q

function of cytoskeleton

A

mobility
movement
contraction
cell division
organelels transprot

shape
surfaces and cell architecture

DYNAMIC

can divide and reassemble

microvili on epithilial cells - structural cables of actin filaments

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3
Q

2 filament systems

A

kinsein and dynein

motor molecules that work w mircotubules

dynein - small gene fam

actin filament and myosin

many diff kinds
myosin and kinesin related in gene fams

duplication and modifacation and many diff purposes

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4
Q

requirements for cytoskelton

A

cytoskeleton filamins - dynami assemble and disassemble

molecular motors + partnered proteins
dynamic filaments
eenrgy

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5
Q

Characterisitics of csk

A

polymers built of self assembling subunits
non covalent interactions
dynamic assembly and disassemble
many interacting proteins regulate structure function
interacting families of motor molecules as atpases for movement
controlled by regulatory kinases and g proteins

no covalent bonds just ionic and electrostatic so monomers and polymbers can be dynamic

all regulated by kinase/exnsyme that transports terminal phosphae from atp onto specific amino acid
where theres kinase there is phosphatase

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6
Q

types of filaments

A

microtubules
- tubulin
made by assembling tubular protein

mircofilaments
filaments
actin
structural support
-made of self assembly of actin protein monomers flobular

intermediate filaments
various proteins
-polarized have finger like microvili -held up by actin filaments

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7
Q

intermediate filaments

A

strong and rope life
strenthen cell against mechanical stress
nuclear envelope suppored by meshwork of filaments
linker proteins connect cytoskeletal filaments and bridge the nuclear envelop
-nuclear lamins

connect w each other

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8
Q

origins of intermediate filament proteins

A

first appeared in lower animals

all have similar rod domain

makes coil coil

N and C terminals are diff depend on type of gene

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9
Q

4 types of intermediate filaments

A

divided into 4 classes
keratins, vimentin, neurofilament proteins, nuclear lamins

all contain an extensive alpha helical rod domain
tissue specificity in the N and C terminal domains

keratin - epithelial cells skin

vimentin - in conentive tissue cells, muscles, and glial
blistering disease
cataract- protein misfold

neurofilaments
in nerve cells
myopathies
onne for now

nuclear lamins
in all animal cells
in every nucleated cell not blood cell bc blood cell spit its nuc in dveleopment
aka blood cells dont have a nucleus
muscular dystrophy

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10
Q

assembly of intermeidate filaments

A

start as dimers
assemble into tetramer

basic building block - coiled-coiled dimer of two aphiphathic helics

have hydrophobic repeating domains

make hydrophobic phase assemble next to each other

helical segments contain heptad repeats in which amino acids A and D are hydrophobic creating a hydropbic face

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11
Q

IF ARE SELF ASSEMBLING POLYMERS

A

monomers assemble w dimers
self assembling rod
no polarity bc N terms not all facing one direction
actin and micrtoubules have polarity

coil dimer winds around each other

2 ends in distinguishable - in opp direction , amino terminal ends away

staggered tetramer
COOHCOOH
two tetramers packeed together
eight twisted to make filamen

connect desmosomes - high tensile strength

only in invertebrates

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12
Q

regulation by phosphorylation

A

no common response
phosphorylation regulates vimentin and lamin diassembly during mitosis in all cells but kerains are ver stable

phosphorylation tend to destablitze

but neurofilaments are stabilized by phosphorylation
depend on type of IF

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13
Q

keratin filaments

A

in epithelial cells attach to cell junctions (desomosomes)

flat and stratified

stem cells ahve basil latyer attached to extracellular matrix

basal layer starts dividing and piles cell layers

network of kerain filaments engables the epitheiliium to function as a sheet of cell

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14
Q

differential expression of keratin sin layers of the skin

A

finally comes coff like peeling skin

skin surface
stratum corneum
granular
spinous
basal
dermis

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15
Q

blistering skin diseases

A

keratin mutations
hyperkeratosis

dealing with mechanical stress

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16
Q

IF and mitosis

A

changes in mitosis

lamen breaks down

and reassmbles afterwards

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17
Q

neurofilaments

A

provide the major structural support for axons

long and skinny

outnumber microtubules in cross section of an axon (transmission EM)

bind to proteins that link them

held up by intermediate filaments

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18
Q

nuclear lamins are a descrete class of intermediate filament

A

has special proteins from inner to outer nuclear mem

form a mesh like netwrok assocaited with the intner nuclear mem

phosphorylation regulates the assembly/diassembly of the network during the cell cycle

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19
Q

sun domain proteins

A

connected to KASH fomains

Kash domains bind to microtubules actin molecular motors

KASH conenct nuclear laims inside nuclear enveleope to filaments in cytoplasm

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20
Q

intermediate filament associated proteins

A

plectin (rod shaped protein connecting intermediate filaments to each other , hemidesomsomes, actin filaments and microtibules)

fillaggrin (aggregates keratin in surface layer of skin

BPAG1 (bullous permphigold antigen, connects keartin to BPAG2 at hemidesmosomes)

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21
Q

plectin

A

conencts IF to acin and microtibules

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22
Q

stretching smooth muscle

A

shows that IFs act as interacellular tendons

allos to come back to resting state

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23
Q

actin movement

A

not motors invovled

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24
Q

actin cytoskeleton

A

part of mvoing vesicles

most cell shape and movement

most abudnant cellular proteins
-actin genes are all very similar and work together

highly conserved sequence and structure - every part of actin gneeded

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25
actin filaments
thin and flexible many proteins bind to actin and modify its properties cortex rich in actin filaments underlies the plasma mem of most euk cells cell crawling depends on cortical actin binding proteins infleunce the type of protursions formed at the leading edge extracellular signals can alter the arrangement of actin filaments actin associates with myosin to form contractile structures
26
infections
need to send macrophage in blood stream bind to endothelial cell blood vessal and crawl inside so macrophage can eat disease actin cytoskeleton need to change dramatically for this to occur
27
actin genes arose in the common ancestor
foudn in all three domains of life evolutionarily old
28
structure of actin molecule
crystal structure 4 domains has atp binding pocket most actin are from single gene alpha alpha beta gama isoforms nearly identical in structure expressed in diff animal cells most monomers self assemble precisely 1+3 recog 2+4 and vice versa monomers that make double strand helix 1+3 expased at one and and 2 + 4 exposed at other polar filament - all filament in one direction
29
actin filaent elongation
association and dissociation rate conastants ATP and ADP polumerize from G in self assmbly process 7-9nm filaments + and - ends one end grows and other does not favors assembly at + end structural and funcational polarity undergoes treadmilling actin monomers are filaments
30
an equilibrium exists between
globular g actin and filamentous f actin in cytoplasm monomers found in 2 states adp or atp bound actin must be complexed with atp to polymerize into filaments only monomers that add to + end is atp bound and free to add on after addition atp is hydrolyzed when adp bound long enough, has tendancy to fall off end grow and other end shrink
31
treadmilling
actin filament actin monomers added to plus end boudn with atp actin filaments break off on minus end boudn with adp works way through filaments
32
nucleation and elongation of adp actin filaments
intermeidiate filaments do not treatdmill need right amount of actin monomers for polymerization the more monomers that lead to assembly until balance of monomers and off rate
33
actin assembly by graph
nucleation phase need 3 monomers to make nucleus actins fump into each other and bind to make nucleus monomers --> nucleus --> f -actin
34
polarity and membranes
actin polarized + end is barbed and adjacent to plasma mem - end is towards innter part of cell + end at membranes lateral attachment at membranes = end free in cytosal
35
actin binding proteins
lots of proteins that bind and help regulate side binding : tropmyosin motors: various mysoin monomer binding, capping, severing w capping, crosslinking, annealing
36
actin filaments and all
porteins that bind to monomer and sequester it = actin monomers nucleate and facilitate assembly = nucleating protein, ex formin and arp cut actin filaments = severing proteins not breaking peptide bands workith with ionic bands can bundle it or make meshwork = cross-linking protein in cell cortex capping -plus end blocking protein = block assembly side bidng protein lysoin motor protein bundling protein -binds to side of actin
37
regulation of nucleotide exchange by actin monomer bidnign proteins
adp - profilin , adf cofilin thymosin profilin atp
38
actin filament nucleation and elongation by formins
+ end adjacent to plasmam mem and up against it formin finds to profilin that is bound to actin reg by g protein fathers profilin actin to make nucleus then knocks off profilin makes filament fh2 binds actin subunits to nucleate a filament filament elongates as actin profilin complexes bind to multiple sites of fh1 and transfer rapidly to the bard end up till her is straight actin bundles
39
formin regualation
making bundles of actin and always same polarity profilin inhibits nucleation, binds to monomers, only atp actin bind cofilin sever protein sever filaments makes new + and - ends tend to depolimarize most of filaments ADP actin aside form gtp, they all work w membranes has lipid site end of actin on mem attached w forman profilin comes off rho is regulator of forman forman has rho binding domain all same polarity at mem
40
actin related proteins
arps - modified actin that can make branches and push mem forward against mem cantpollymerize to make filamens works w other structures to nucleate signals a dozen other familes of arps dynactin complex
41
adaptoer protein
cdc42 has lipid anchor = active can interact w diff proteins w diff domains activated arp 23 can bind to side of actin filaments conserved structure - can be used to make new nucleus mesh work at plasma mem
42
cofilin and assembly
cofilin interculates between adjacent monomes in filamens and breaking it only at starting end monomers can be reutilized no moto proteins at play actin drives mobility
43
nucleation of branched acin filaments by Arp 2/3 complex
activated by wasp complex which acterated by csc42 binds to filament and wasp comes off wasp /scar nucleation promoting factor bidns an actin monomer then arp 2/3 complex
44
wasp
nucleation promoting factor auto inibited fold and wont work until activated by cds42 psydopods give polarity to actin network of cell signaling bacterium wasp wade triggers process making branches to mvoe cell polymerize and push cell forward cells need to attach to substrate
45
actin binding porteins capping q
binds to ends to block assembly or stablize filaments finds to - prevents disassmbly binds to minus end to block disassembly combined profilin and capping protsins maintan an actin ponomer pool profilin bidning to onomer to buffer so can maintain legth and identity
46
severing with capping
severing mechanism disolved acting filaments requires sodium way of shriaking actin filaments get in bteween and break apart severing to capping protein same
47
crosslinking
muscular dystrophy protein in lab made meshwrok of actin in musle cells ` makes cordical cells that have not migratory ****
48
cant mess w actin system like you can microtubules
cytochalasin -depolymarize pinching off - binds monomers and barbed ends, inhibit polymerization latrunculin - binds monomers and inhibits polymerization phalloidin - binds and stablizes filaments, ca drug ck666 inhibits arp 2/3 problem is every celll has actin discover contractile ring
49
regulation of acin assembly by rho family gtpase
rho modulate bundle w foreman repond to external signal cdc42 can know which cell behaves activated form os cdc42 rac and rho have diff effects on actin filaments
50
microtubules
translocate vesicles in cells, organizing ER network ciliart and flagellar beat transport of vesicles in cytoplasm alignment and seperation of chromosomes cell structure and support found in a variety of ways and organization in cells cilia and flagella axons mitotic apparatus ratiate arrays can sprawl out from centrioles
51
microtubule structure
globular tubulin subunit 55kD alpha beta heterodimers with exchangeable gtp bidning site 13 protofilaments per tubule polar 1 end alpha 1 end beta made of self assemble proteins into tubules actin 42 monomers made of dimers dimers polymarize and make frotofilaments that make up mircotubul
52
building a microtubule
dimers of tubulin with bound gtp add to the plus end of the growing tubules at mins end are found to gdp due to intrinsic gtpase activiy of ubulin polar filaments tubulin is kind of an enzymes
53
tubulin binding drug
colchicine, nocodazole --> binds tubulin dimers and inhibits polymerization taxol -kemo - binds and stabilizes microtubules used for cancer chemotherapy - mucks up dividing cells
54
tubulin gene families
ftsZ bacterial tubulin relative forms polymers for cytokinesis alpha beta tubulin - heterodimers form mircotibules in eukaryoes gama tubulin - major component of tublin ring complex in cetrosome mircotuble organizing center
55
polymerization of pure tubulin microtubules
can change conc and observe growth need to be gtp bound to add
56
polymerization followed by nucleoside hydrolysis
minus end addtion is slow andhydrolysis catches up plus end addition is fast and hydrolysis lags behind
57
microtubules treadmill and undergo catasrtophe
growth slower than disassembly dynamic instablity at cc dyn insta gtp cap at + end = stable gdp cap = disassembly micro stable as long at tubulin dimers has gtp bound to them
58
MT growing and shrinking
gtp binders help to grow MT add to growing end and addition proceeds faster than gtp hydrolysis by the dimers shrinking - proliferation containing gdp peel away from wall tubulin released to cytosol dont want ot polymarize all at once dynamic instability -growing and shrinking -- in all cells w microtubules
59
microtubule binding proteins
some stabilize or block tau stabilizes - lots in brain binds side and stabilizes MT lots of tau in neurons and axons modified tau in alxheimers katinin destabilizes AAA Atpase that severs microtubules multi drug resist porteins surfing maps first binding protein MAPS2 in dentrites
60
MTs assemble form organizing centers
mtoc centrosome i end at mtoc turc nucleates MT below critical conc unique group of proteins at centrosome related to gamma tubulin (actin) that leads to polymerization all branching out are grow at + end
61
centrosomes
pericentriolar mateiral pcm gamma tubulin ring complex nucleate numaraization mother centriole within centrosome - cell divisn = duplication adjacent to nucleus dendrites have mixed polarity axon has mts of uniform polairty
62
centrosomes and basal bodies
basal bodies = pair of centrioles nucleats cilia serve as MTOCS
63
microtubules are stablized when a capping protein
captures the plus end of a MT coritcal cappping protin complex includes dynein motor and its dynactin complex, able to orient mitotic apparatus
64
pathway of centriole duplation during cell cycle
mother/daughter ck2cylin E centrin procentriole gama tubulin late g2/M prophase mother dauther migration apart
65
centrosome maturation as a cell enters mitosis
66
MT branching
microtubulin binding protiens combine w augmins to make branched microtule networks recruits tubulin ring complex

Cell Bio (3 decks)

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