White: Cytoskeleton 1&2

Question 1

Hereditary spherocytosis and anemia

Answer 1

Diseases caused by defect in RBC cytoskeleton- Spectrin

Question 2

Cytoskeletal filaments consist of

Answer 2

Multiple protofilaments

Question 3

Actin filaments

Answer 3

Like mardis gras beads

Determine shape of cells surface and are necessary for whole-cell locomotion, secretion and endocytosis

Question 4

Microtubules

Answer 4

Slinky of life
Determines the positions of membrane-enclosed organelles
Directs intracellular transport
Make up centrioles and mitotic spindle
Make up cilia and flagella
One end attached to organizing center-centrosome

Question 5

Intermediate filaments

Answer 5

Girders of life-rope like properties
Strong filament, provides mechanical strength
Resists mechanical stress
Allows formation of hairs and fingernails

Question 6

Polarity for intestinal cells is maintained by

Answer 6

The cytoskeleton

Question 7

Microvilli increase surface area by __X

Answer 7

4x

Question 8

Cytoskeletal polymers are held together by _____ which means what

Answer 8

Weak noncovalent interactions, which means that their assembly and disassembly can occur rapidly

Question 9

______ are stiff and difficult to bend

______ are flexible and easily bent

Answer 9

Microtubules are stiff and difficult to bend

Actin filaments are flexible and easy to bend

Question 10

Nucleation

Answer 10

Initial process in polymerization of actin filaments and microtubules

Question 11

Nucleoside hydrolysis leads to

Answer 11

Treadmilling and dynamic instability

Question 12

Treadmilling predominates in

Answer 12

Actin filaments

Question 13

Catastrophe

Answer 13

Change from rapid growth to rapid shrinkage

Question 14

Rescue

Answer 14

Change from rapid shrinkage to rapid growth

Question 15

Hydrolysis of GTP changes

Answer 15

Conformation of the subunits, making protofilaments curved, which can then be easily depolymerized

Question 16

Dynamic instability predominates in

Answer 16

Microtubules

-This is important in separation of chromosomes during mitosis

Question 17

Intermediate filament formed by

Answer 17

Eight parallel tetramers (protofilaments) packed together laterally

Question 18

Rate-limiting step in formation of cytoskeletal filament

Answer 18

Nucleation

Question 19

ARP complex

Answer 19

In presence of activation factor, nucleates actin filament growth from the minus end, allowing elongation at the plus end

• Bypasses rate limiting step of nucleation
• Branches at 70 degree angle
• Used in Listeria

Question 20

Formin

Answer 20

Nucleates the growth of straight and un-branched actin filaments
Remains associated with rapidly growing plus end as it elongates

Question 21

Thymosin

Answer 21

Binds actin subunits, preventing assembly into polymer

Question 22

Profilin

Answer 22

Recruits actin monomers to the actin filament for polymerization
Exposes the site of actin that binds to the plus end

Question 23

Tropomodulin

Answer 23

Prevents assembly/disassembly at minus end (stabilizes actin filaments) for long lived filament stabilization

Question 24

Tropomyosin

Answer 24

Stabilizes filament, prevents binding with other proteins

Question 25

Capping protein

Answer 25

Prevents assembly/disassembly at plus end

Question 26

Cofilin

Answer 26

Binds ADP-actin, accelerates disassembly

Question 27

Gelsolin

Answer 27

Severs actin filaments and binds to plus end | Helps with new and rapid assembly or disassembly

Question 28

Actin is organized into which two types of arrays

Answer 28

Bundle and web-like (gel-like) networks

Question 29

Alpha-actinin

Answer 29

Bundling protein- cross links actin filaments into loose bundles, allowing myosin II to enter to make actin filaments contractile

Question 30

Fimbrin

Answer 30

Bundling protein- Cross- links actin filaments into tight bundles, excluding myosin II

Question 31

Filamin

Answer 31

Promotes the formation of loose, highly viscous gel-like networks by clamping together 2 actin filaments at right angles Cells require actin gel in order to extend membrane projections Helps cells to crawl, cannot crawl without filamen

Question 32

Filamin helps cells

Answer 32

Crawl across a solid surface | Cells require the actin gel in order to extend membrane projections

Question 33

Spectrin

Answer 33

Attaches cytoskeleton to membrane in RBC

Question 34

ERM family

Answer 34

Ezrin, Radixin, Moesin | Mediates the attachments b/w actin and plasma membrane

Question 35

Stathmin

Answer 35

Binds microtubule subunits, preventing assembly

Question 36

TIPS

Answer 36

The plus end tracking proteins | Remains associated with growing plus ends and can link them to structures such as the membrane

Question 37

y-TuRC

Answer 37

y-tubulin ring complex | Nucleates assembly and remains associated with minus end

Question 38

Katanin

Answer 38

Severs microtubules

Question 39

MAPs

Answer 39

Stabilizes microtubules by binding along sides

Question 40

XMAP215

Answer 40

Microtubule associated protein that stabilizes plus ends and accelerates assembly Inhibits switch from growing to shrinking state

Question 41

Kinesin 13

Answer 41

Enhances catastrophic disassembly at plus end

Question 42

MAPs have __ domains

Answer 42

2 domains, one that binds microtubule and one that projects outward

Question 43

Plectin

Answer 43

Cross-linking protein, links microtubules to intermediate filaments

Question 44

Tau

Answer 44

MAP protein, forms bundles of more closely packed microtubules Binds microtubule at both its N- and C- termini Has short projecting loop

Question 45

MAP2

Answer 45

Long projecting domain Second microtubule binding domain at other end Forms bundles of stable microtubules that are kept widely spaced

Question 46

Cytoplasmic dynein

Answer 46

Vesicle trafficking, localization of the golgi apparatus

Question 47

Axonemal dynein

Answer 47

Specialized for rapid and efficient sliding movements of microtubule that drive the beating of cilia and flagella

Question 48

Microtubule nucleation at the centrosome is mediated by

Answer 48

y-tubulin

Question 49

Actin filaments are nucleated near

Answer 49

The plasma membrane- mediated by ARP complex and formin