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Cell Bio > Exam 2 - mod 6 > Flashcards

Exam 2 - mod 6 Flashcards

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Biology 101 flashcards
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
Q

actin filaments

A

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

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26
Q

infections

A

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

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27
Q

actin genes arose in the common ancestor

A

foudn in all three domains of life

evolutionarily old

28
Q

structure of actin molecule

A

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
Q

actin filaent elongation

A

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
Q

an equilibrium exists between

A

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
Q

treadmilling

A

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
Q

nucleation and elongation of adp actin filaments

A

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
Q

actin assembly by graph

A

nucleation phase
need 3 monomers to make nucleus

actins fump into each other and bind to make nucleus

monomers –> nucleus –> f -actin

34
Q

polarity and membranes

A

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
Q

actin binding proteins

A

lots of proteins that bind and help regulate

side binding : tropmyosin
motors: various mysoin

monomer binding, capping, severing w capping, crosslinking, annealing

36
Q

actin filaments and all

A

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
Q

regulation of nucleotide exchange by actin monomer bidnign proteins

A

adp - profilin , adf cofilin thymosin profilin
atp

38
Q

actin filament nucleation and elongation by formins

A

+ 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
Q

formin regualation

A

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
Q

actin related proteins

A

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
Q

adaptoer protein

A

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
Q

cofilin and assembly

A

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
Q

nucleation of branched acin filaments by Arp 2/3 complex

A

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
Q

wasp

A

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
Q

actin binding porteins capping q

A

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
Q

severing with capping

A

severing mechanism
disolved acting filaments
requires sodium

way of shriaking actin filaments

get in bteween and break apart
severing to capping protein same

47
Q

crosslinking

A

muscular dystrophy protein in lab
made meshwrok of actin in musle cells `

makes cordical cells that have not migratory
**

48
Q

cant mess w actin system like you can microtubules

A

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
Q

regulation of acin assembly by rho family gtpase

A

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
Q

microtubules

A

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
Q

microtubule structure

A

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
Q

building a microtubule

A

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
Q

tubulin binding drug

A

colchicine, nocodazole –> binds tubulin dimers and inhibits polymerization
taxol -kemo - binds and stabilizes microtubules used for cancer chemotherapy - mucks up dividing cells

54
Q

tubulin gene families

A

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
Q

polymerization of pure tubulin microtubules

A

can change conc and observe growth

need to be gtp bound to add

56
Q

polymerization followed by nucleoside hydrolysis

A

minus end addtion is slow andhydrolysis catches up

plus end addition is fast and hydrolysis lags behind

57
Q

microtubules treadmill and undergo catasrtophe

A

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
Q

MT growing and shrinking

A

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
Q

microtubule binding proteins

A

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
Q

MTs assemble form organizing centers

A

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
Q

centrosomes

A

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
Q

centrosomes and basal bodies

A

basal bodies = pair of centrioles nucleats

cilia serve as MTOCS

63
Q

microtubules are stablized when a capping protein

A

captures the plus end of a MT
coritcal cappping protin complex includes dynein motor and its dynactin complex, able to orient mitotic apparatus

64
Q

pathway of centriole duplation during cell cycle

A

mother/daughter
ck2cylin E
centrin
procentriole
gama tubulin
late g2/M
prophase
mother dauther
migration apart

65
Q

centrosome maturation as a cell enters mitosis

A
66
Q

MT branching

A

microtubulin binding protiens
combine w augmins to make branched microtule networks
recruits tubulin ring complex

Cell Bio (3 decks)

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