Cytoskeleton

Question 1

Cytoskeleton Roles (5)

Answer 1

Cellular polarity & shape
Directional migration
Formation of mitotic/meiotic spindle
Chromosome segregation
Cytokinesis

Question 2

Cytoskeleton components:

Answer 2

Intermediate filaments
Actin
Microtubules

Question 3

Intermediate Filaments location (4)

Answer 3

Surround nucleus
Extend to cell periphery
At cell-cell junctions
At cell-ECM junctions

Question 4

Intermediate Filaments Structure

Answer 4

2 chained coiled coil that forms an antiparallel tetramer

Question 5

Examples of Intermediate Filaments(3)

Answer 5

Keratin
Neurofilaments
Nuclear lamins

Question 6

Intermediate Filaments

Answer 6

Controlled by phosphorylation (dynamic)

Role in signaling and controlling gene regulatory networks

Question 7

Actin Filaments

Answer 7

Polymers of actin with ATP or ADP bound
Helical
Polar (barbed and pointed end)

Question 8

Microtubules

Answer 8

Polar
Binds GDP or GTP
Polymers of alpha/beta tubulin arranged in tubules with 13 protofilaments

Question 9

Microtubule examples (5)

Answer 9

Mitotic spindle
Cilia
Flagella
Basal bodies
Centrioles

Question 10

ATP/GTP cap

Answer 10

At growing end

Due to nucleotide hydrolysis lagging behind polymerization

Question 11

Phalloidin (natural toxin)

Answer 11

Bind and stabilize actin filaments

Question 12

Colchicine (natural toxin)

Answer 12

Depolymerize microtubules

Question 13

Taxol (natural toxin)

Answer 13

Bind and stabilize microtubules

Question 14

Microtubule growth stabilized by ______ and destabilized by _____ which leads to _________

Answer 14

Stabilize: GTP tubulin cap at + end
Destabilize: GDP tubulin at + end
Leads to: rapid depolymerization

Question 15

+ tip proteins

Answer 15

Inhibit catastrophes to let microtubules get to cell periphery

Question 16

Primary cilium

Answer 16

Non-motile sensory organelles

Role in developmental signaling pathways

Question 17

MAPs

Answer 17

Microtubule Associated Proteins

Question 18

MAPs regulate __________ and can ________

Answer 18

Microtubule assembly

Stabilize or destabilize the + and - end

Question 19

Actin polymerization provides

Answer 19

Force for movement

Question 20

How to get force for movement (3)

Answer 20

Nucleation more actin filaments
Sever existing filaments to create more barbed ends
Form branches from existing actin filaments

Question 21

Are 2/3 is activated by ______ and is required for _______

Answer 21

Rho (downstream)

Nucleation of actin polymerization

Question 22

Are 2/3 involved with (3)

Answer 22

Wound healing
Neutrophil migration
Invasion of metastatic cancer cells

Question 23

Cytoskeletal Motors

Answer 23

Myosin (actin)
Kinesin (microtubule)
Dynein (microtubule)

Question 24

Cytoskeletal motors are all ________

Answer 24

ATPases

Create conformational change by binding ATP to make mechanical work

Question 25

Myosin V

Answer 25

Carries cargos on tail

Question 26

Myosin I

Answer 26

Single headed myosins | Bind to plasma membrane

Question 27

Myosin II

Answer 27

Form bipolar filaments Each power stroke moves myosin 1 actin subunit closer to + end Filament that forms myosin

Question 28

Myosin moves towards

Answer 28

+ end of actin

Question 29

Myosin roles (3)

Answer 29

Cytokinesis Intracellular transport Endocytosis

Question 30

Myosin globular head has _______ and the tail binds to _______ and is ______

Answer 30

ATPase Membrane/target Variable

Question 31

Kinesin moves towards

Answer 31

+ end of microtubule

Question 32

Kinesin head has ______, the tail binds _______ and is _______, the neck region determines _________

Answer 32

ATPase Target Variable Polarity (next to head)

Question 33

Dynein moves towards

Answer 33

- end of microtubule

Question 34

Dynein is found in

Answer 34

Cilia and flagella arms for beating

Question 35

Primary Ciliary Dyskinesia (PCD)

Answer 35

Cilia are immobile Male sterility and respiratory tract infection Mutation in outer arm ciliary dynein heavy chain

Question 36

Dynein is used for

Answer 36

Retrograde axonal transport

Question 37

Transporting vesicles

Answer 37

Involves dynein, kinesin, myosin V | Transfer from microtubule to actin

Question 38

Intracellular transport from _____ to ______

Answer 38

ER to cell periphery (and back)

Question 39

Intracellular transport occurs on ______ via _______

Answer 39

+ end of microtubule | + tip protein to prevent catastrophe

Question 40

Melanosomes need ______ to be transported to ______

Answer 40

Myosin V | Cell periphery

Question 41

In melanosomes, myosin V binds cargo using _______

Answer 41

Melanophilin and Rab-GTP | Rab-GTP binds to receptor on cargo

Question 42

Griscelli Type 1

Answer 42

Mutation in myosin V, melanophillin or Rab-GTP | Silver hair, light skin, neuro defects