Cytoskeletal Motility

Question 1

Types of Intermediate Fillaments

Answer 1

Keratin, Vimentin, Neurofilaments

Question 2

Where is Keratin Expressed

Answer 2

Epithelial Cells

Question 3

IF provide?

Answer 3

tensile strenght and allow cells to withstand mechanical strength

Question 4

Which of Cytoskeletal Elements are toughest?

Answer 4

Intermediate Filaments

Question 5

Vimentin

Answer 5

Found in mesenchymal Cells
Associate with microtubules via accessory proteins
Maintain cell organizanization

Question 6

Neurofilaments

Answer 6

Fill the core of neuronla axons

Question 7

Lamins

Answer 7

Line and strengthen the inside surface of the INNER nuclear membrane

Question 8

Nuclear Lamina

Answer 8

Disassembles and re-forms at each cell division
Phosphorylation Weakens the binding between the tetramers and causes the filaments to fall apart
Dephosphorylation at end of mitosis causes the lamins to reasemble

Question 9

Intermediate Dependent molecular motors

Answer 9

DO NOT EXIST

Question 10

Cross Links of IF to MT

Answer 10

Caused by Plectin

Question 11

IF found in

Answer 11

Desomosomes

Question 12

Microtubules

Answer 12

Long and relatively stiff HOLLOW tubes of protein that can rapidly dissassemble in one location and resasemble in another
Has Polarity: is essential to provide a track for directed movement

Question 13

Microtubules Structure

Answer 13

tubulin: a dimer of two similar globular proteins
alpha and beta tubulin
tubulin has 13 tubulin protofilaments
each protofilament has a + and - end

Question 14

Dynamic Instability

Answer 14

Microtubules innate ability to disassembe and reassemble
Comes from intrinsic capcity of tubulin molecules to hydrolyze GTP
Tubulin with GTP pack tightly
Tubulin with GDP doesn’t pack tightly

Question 15

Colchicine

Answer 15

Binds tightly to free tubulin and prevents its polymerization of microtubules

Question 16

Taxol

Answer 16

tightly binds to microtubules and prevents them from losing subunits
Lock in GTP conformation
Microtubules can grow, but cannot shrink

Question 17

Method of Microtubule Growth

Answer 17

Like a fisherman casting out reel

Question 18

Motor Proteins

Answer 18

Kinesins, Dyneins, Myosin
ATP-binding heads and tails
Heads have ATPase
Exhibit Polar Motility

Question 19

Kinesins:

Answer 19

Motor proteins that move along microtubules to the + end

Question 20

Dyneins

Answer 20

Motor proteins that move along microtubules to the -end

Question 21

Microtubules Built From…..

Answer 21

Direct growth from Centriole or

Growth from gamma tubulin ring

Question 22

Microtubule Associated Proteins

Answer 22

Promote asembly and stabilize microtubules

Define Microtubule spacing within cell processes

Question 23

Cilia

Answer 23

Hairlike Structure ~0.25 um that move fluid over the surface of a cell or to propel a single cell through a fluid

Question 24

Flagella

Answer 24

used for locomotion and do not have sweeping motion but whip like
Arranged in nine double microtubules in a ring aorund a pair of single microtubules (9+2)
Nexin attaches microtubules so that ATP binding causes sliding rather than bending

Question 25

Actin

Answer 25

inherent polarity, rarely occur in isolation in the cell; generally found in cross-linked bundles and networks

Question 26

Growint actin filament

Answer 26

Use ATP, once ATP is hydrolyzed to ADP, actin monomer is less stable and reduces the strength of the binding between monomers

Question 27

Cytochalasin & Phalloidin

Answer 27

Inhibits actin polymerization

Question 28

Thymosin & profilin

Answer 28

Prevent Free actin monomers from polymerizing

Question 29

Actin Related Proteins

Answer 29

Allow for Branching

Question 30

Control of Actin

Answer 30

Actin arrays controlled by Rho GTPases (Rac, Rho, CDC42)

Myosin and Kinesin are related to Ras GTPase

Question 31

Polarity of Kinesin Family Motors

Answer 31

N-Terminal motor = + End Directed
C-Terminal Motor = - End Directed
Internal Motor = MT depolymerizing Activity

Question 32

Myosin

Answer 32

Moves vessicle towards + End

Question 33

Dynein Involved In

Answer 33

Mitosis, Nuclear Envelope Breakdown, vesicle/particel transport, golgi maintenance

Question 34

Dynein

Answer 34

Moves vessicle towards - End

Question 35

Dynactin

Answer 35

Adaptor protein that binds cytoplasmic dynein to vesicles