Cytoskeleton 2

Question 1

Intermediate Filament Function

Answer 1

Cell structure, localization of cellular processes.

Anchors cells

Question 2

Intermediate filament structure

Answer 2

Central rod domain (a helix), amino head,carboxy tail.
Strongest and most stable cytoskeleton protein
Forms network

Question 3

Keratin expressed in

Answer 3

Epithelial cells

Question 4

Intermediate filament assembly

Answer 4

Dimers —> tetramer (anti parallel and staggered) -> protofilament —> 8 protofilaments form filament from both ends

Question 5

Epidermolysis bullosa simplex (EBS)

Answer 5

Most common and mildest EB.

Keratin defective, skin splits at epidermis causing blisters

Question 6

Microtubules assembly

Answer 6

• Dimers of hollow a and B tubulin polymerizing using GTP to give microtubules.
• 13 protofilaments arranged around hollow core.
• (+) and (-) end

Question 7

Dynamic instability of Microtubules

Answer 7

• individual microtubules alternate between growth and shrinkage.
• GTP-tubulin added faster than GTP cleaved then growth and vice versa.
• rapidly = “catastrophe”

Question 8

Microtubule Centrosome

Answer 8

Organizing center, initiates growth.

-binds (-) end and allow growth toward plasma membrane

Question 9

y-tubulin

Answer 9

Key protein for microtubule growth from centrosome.

Question 10

Microtubule stability

Answer 10

Unstable but stabilized by post translation modifications and microtubule associated proteins (MAPs)

Question 11

MAPs (polymerases/depolymerases) 5 things

Answer 11

• Specific.
• regulate microtubules by capping ends
• speeds up assembly/dissembly by increasing/dissociating GTP tubulin at (+) end
• connect microtubules to IFs or plasma membrane
• binds to GTP and moves growing microtubules

Question 12

CLASP

Answer 12

An MAP that rescues microtubules from catastrophe by stopping disassembly and restarting growth at (+) end.
- clamps around microtubule

Question 13

Microtubule that sends signals in nerve cells

Answer 13

Axons. Project from cell body

Question 14

Microtubule that receives signals in nerve cells

Answer 14

Dendrites. Project from cell body.

Question 15

Axons

Answer 15

(+) end away from main part (cell body)

• (-) end not anchored in centrosome
• capped at both ends
• Contain tau protein that stabilizes

Question 16

Tau Protein

Answer 16

Stabilizes microtubule (axon)

Question 17

Dendrites

Answer 17

Oriented in both directions.

Contain MAP-2 protein

Question 18

MAP-2 protein

Answer 18

Cross links microtubules to IFs in dendrites

Question 19

Microtubule Motor Proteins

Answer 19

Dynein, kinesin, cilia, flagella.

ATP hydrolysis required for movement

Question 20

Dynein

Answer 20

Microtubule motor protein that moves towards (-) end.

• transports macromolecules, organelles, vesicles towards center of cell
• ATP hydrolysis required

Question 21

Kinesin

Answer 21

Motor protein that moves towards (+) end, transports macromolecules, vesicles, and organelles away from center of cell
-ATP hydrolysis required

Question 22

Cilia

Answer 22

Microtubule projection of plasma membrane.

-beat in coordinated fashion to move fluid over cells

Question 23

Flagella

Answer 23

Microtubule projection of plasma membrane, sperm locomotion.

Question 24

Cilia and Flagella Structural components

Answer 24

Axoneme (9+2, A and B, radial spokes, dynein) and Basal body (centriole and 9 triplets)

Question 25

Axoneme (cilia and flagella)

Answer 25

- central pair of microtubules surrounded by 9 doublets (9+2) - doublet consist of A tubule (complete) and B tubule (incomplete) - doublets connected by NEXIN and to central pair by radial spokes. - Each A attached to dynein

Question 26

``` Basal Body (cilia and flagella) Structure and function ```

Answer 26

- anchors (-) end inside cell. - modified centriole (organization center) - 9 triplets of microtubules - initiate growth of axonemal microtubules and dictates position and orientation of cilium

Question 27

Microtubule disease, MAP tau form aggregates in

Answer 27

Alzheimer’s

Question 28

Microtubule disease smoking

Answer 28

Damages cilia in trachea and bronchial tubes in lungs

Question 29

Primary Ciliary Dyskinesia

Answer 29

Rare genetic microtubule disease where cilia is lacked or dysfunctional. -chronic upper and lower respiratory tract distress shortly after birth, cough, nasal discharge

Question 30

Cancer drugs

Answer 30

Affect microtubule assembly and dissembly