Cytoskeleton

Front 1

Function of Actin

Back 1

cell shape
migration
phagocytosis

Front 2

Function of Microtubules

Back 2

Positioning of organelles
intracellular transport
cell motility (cillia and flagella)

Front 3

Function of Intermediate Filaments

Back 3

Mechanical Strength

Front 4

explain the protofilament advantage

Back 4

If assembled into only one line of monomers, only need to break one bond to disrupt filament. If assembled into multiple with x filaments, need to break x bonds to break vertically and need to break 3 bonds to remove a monomer. greatly increases strength

Front 5

polarity of actin

Back 5

+ end and - end
C terminus and N terminus are both on the plus end

Front 6

What form of ATP/ADP do actin monomers contain?

Back 6

ATP

Front 7

Treadmilling

Back 7

have addition on plus end and subtraction from minus end Monomer concentration must be above the critical concentration of the plus end and below the critical critical concentration of the minus end

Front 8

ARP

Back 8

an actin nucleation protein Actin related protein complex nucleates at minus end and binds the preexisting filaments at 70 degree angles ARP23 binds minus aend and get efficient growth from the plus end also stabilizes the minus end

Front 9

Profilin

Back 9

binds free actin monomers and promotes rapid plus-end growth
Competes with thymosin for growth equilibrium

Front 10

Thymosin

Back 10

binds free actin monomers and prevents addition to plus end therefore preventing growth from the plus end
competes with profilin for equilibrium

Front 11

Cofilin

Back 11

Actin depolymerization factor
preferentially binds ADP bound actin in helix which are most likely to be found in older filaments, makes a kink in the helix and makes degredation more likely

Front 12

CapZ

Back 12

binds and caps the plus end. this allows addition to the minus end only and requires a much higher critical concentration for growth

Front 13

3 arrangments of actin

Back 13

antiparallel
gel-like network
tight parallel bundle

Front 14

antiparallel

Back 14

alternating plus end and minus end orientation
often in contractile tissue
uses alpha actinin to make 3d arrangment

Front 15

gel-like actin network

Back 15

often helps form lamellipodia
many different angles of orientation
uses filamin and spectrin

Front 16

Tight parallel bundle actin arrangement

Back 16

often in cell projections and can tell what type ex: cilia or flagella based on arrangment
fimbrin is the orientation protein, forms at no angle so tightly bound together

Front 17

ERM

Back 17

binds actin and transmembrane protein
regulated by phosphorylation or PIP2 binding and will allow phosphorylated actin to bind to a transmembrane protein
has an actin binding domain, an alpha helical domain and a membrane binding domain

Front 18

Phalloidin

Back 18

a drug that binds actin filaments
prevents filament shrinkage

Front 19

Myosin

Back 19

molecular motor of actin that moves toward the plus end
bipolar thick filament arranged in light and heavy chains two heavy chains and four light changes with two head domains

Front 20

Myosin contraction steps

Back 20

1 head bound in absence of ATP
2 ATP binds and head releases
3 ATP dissociates to ADP and P
4 Phosphate leaves head attaches
5. ADP leaves and causes power stroke

Front 21

Microtubule structure

Back 21

alpha and beta tubulin monomers with a plus end and minus end
usually anchored at minus end at MTOC
usually thirteen filaments arranged in a hollow tube structure
microtubule subunit is a heterodimer of alpha and beta tubulin
binds GTP/GDP

Front 22

MTOC

Back 22

a microtubule organizing center in the centrosome and basal body made of gamma tubulin ring structures centrosome and basal body are oriented differently

Front 23

What GTP/GDP form is bound to free microtubule subunits

Back 23

GTP

Front 24

Microtubule dynamics

Back 24

initially have a GTP cap, if hydrolysis of GTP cap goes too fast and catches up with GDP, will have catastrophe
Rescue occurs when rebuild the GTP cap

Front 25

Taxol

Back 25

anti cancer drug that stablizes microtubules so can't enter into the cell cycle

Front 26

Kinesin

Back 26

microtubule motor moves toward the plus end of the microtubule ER
kinesin in dimer form, there is a leading head and a lagging head hand over hand processivity
attached 50% of the time
exchange of ATP to ADP cause the movement of the other head

Front 27

Dynein

Back 27

microtuble motor protein minus end directed
move cytoplasmic and are involved in vesicle transport and movement of golgi
rapid movement of flagella and cilia

Front 28

Flagella

Back 28

9 doublets around 2 singlets, the basal body doesn't have the two singlets
moves in wave like movement
contain minus directed dynein motor proteins in the inside

Front 29

cilia

Back 29

moves in whiplike movement
9 doublets with two singlets in the middle
main structure called an axoneme
anchored in basal bodies
has dynein in the middle

Front 30

Linked vs not movement

Back 30

linked microtubules will move by bending when add ATP for dynein
not linked will slide past eachother when ATP is added
flagella has linked microtubles

Front 31

Kartagener’s Syndrome:

Back 31

defective dynein proteins causes male sterility

Front 32

basal bodies

Back 32

have 9 triplets but no central microtubules

Front 33

Intermediate filaments

Back 33

nonpolar have a alpha helical monomer which forms a coiled coil dimer which then backs together and all coils together for strenght
mechanical support is primary support
assembly is regulated through phosphorylation

Front 34

types of intermediate filaments

Back 34

nuclear- lamina
epithelial- keratin
axonal- neurons
vimentin-like- muscles mesenchyme and glial cells

Front 35

keratin

Back 35

connects cells by desmosomes
accounts for Epidermolysis Bullosa Simplex which causes blistering of the epidermis

Front 36

Intermediate Filament Crosslinking

Back 36

C-terminus binds other filaments
bundled are called tonofilaments
also have accesory proteins

Front 37

Filaggrin

Back 37

Filament Aggregation

Front 38

plectin

Back 38

binds the cytoskeletal elements together

Front 39

Focal Contacts

Back 39

actin linked to extracellular matrix by integrins

Front 40

Adherins Junctions

Back 40

Actin linked to other cells via cadherins
cell cell adhesion

Front 41

Hemidesmosomes

Back 41

Intermediate filaments linked to extracellular matrix via integrins

Front 42

Desmosomes

Back 42

Intermediate filaments (tonofilaments) linked to other cells via desmosomal cadherins

Front 43

Location of actin

Back 43

Beneath plasma membrane
Cortical Actin

Front 44

Location of Microtubules

Back 44

From single origin throughout the cell from the centrioles and the basal bodies

Front 45

Location of Intermediate Filaments

Back 45

Spanning cytoplasm and beneath nuclear membrane