Cto - Cytoskeleton

Front 1

what are the 3 major cytoskeleton elements?

Back 1

1) actin
2) microtubules
3) intermediate filaments

Front 2

F-actin is a polymer version of which type of actin?

Back 2

Globular actin (G-actin)

Front 3

what is the approximate diameter of actin filaments?

Back 3

7nm

Front 4

what are the two major ways actin is used in the cell?

Back 4

1) cellular motility
2) strucutal scaffolding

Front 5

what occurs at the + and - ends of actin filaments during steady state?

Back 5

units of G-actin are added at the + end and lost at an equal rate at the - end

Front 6

of what is a microfilament of actin composed?

Back 6

2 fibers of F-actin which are wound around each other.

Front 7

via which 2 molecule classes do actin filaments participate in cell-cell interactions and cell-substrate interactions, respectively?

Back 7

cell adhesion molecules; integrins

Front 8

what is the role of cytochalasins?

Back 8

they disrupt actin filament polymerization, allowing scientists to study the roles actin plays in the cell.

Front 9

what is phalloidin? what impact does it have on polymerization?

Back 9

a drug which stabilizes F-actin; it prevents depolymerization

Front 10

microtubules are composed of heterodimers of which molecules?

Back 10

alpha and beta tubulin

Front 11

how big are the filaments of microtubules?

Back 11

25nm

Front 12

how many protofilaments, composed of heterodimers, are in one microtubule?

Back 12

13 protofilaments

Front 13

where is the microtubule organizing center (MTOC) located?

Back 13

in the centrosome

Front 14

do microtubules play motility roles in the cell in addition to their structural roles?

Back 14

yes

Front 15

kinesin and dynein are part of which class of proteins?

Back 15

microtubule-associated proteins (MAPs)

Front 16

does kinesin bring material toward the + or - end of microtubules? dynein

Back 16

kinesin brings material toward the + end (out of the cell) and dynein brings material toward the - end (into the cell)

Front 17

what is the microtubule analog for phalloidin? for cytochalasins?

Back 17

Taxol; colchicine

Front 18

how thick are intermediate filaments?

Back 18

approximately 10nm

Front 19

what is the primary role, structural or motility, of intermediate filaments?

Back 19

structural

Front 20

why don't intermediate filaments exhibit polarity?

Back 20

because they are stacked in an antiparallel fashion

Front 21

where in the structure do intermediate filaments exhibit the greatest level of diversity?

Back 21

at the C- and N- termini

Front 22

is ATP hydrolysis necessary for polymerization of depolymerization of actin filaments?

Back 22

depolymerization

Front 23

which microfilament plays an important role in forming contractile ring during telophase?

Back 23

actin

Front 24

which two types of cellular "feet" do actin filaments compose?

Back 24

filopodia and lamellipodia

Front 25

why do molecules at the - end of microfilaments fall off more quickly than those at the + end?

Back 25

because they are bound to ADP instead of ATP. (bound ADP promotes depolymerization)

Front 26

what class of proteins help actin to form a structural scaffolding network?

Back 26

actin binding proteins

Front 27

which proteins are essential in anchoring actin filaments?

Back 27

integrins

Front 28

which element of cytoskeleton is most intimately involved in shaping the cell membranes and is consequently found in large amounts below membrane surface?

Back 28

actin

Front 29

which are hollow, actin, intermediate filaments, or microtubules?

Back 29

microtubules

Front 30

at which end of microtubules does most polymerization take place? depolymerization?

Back 30

both take place at + end because - end is anchored

Front 31

is microtubule depolymerization and polymerization controlled by ATP or GTP hydrolysis?

Back 31

GTP;

Front 32

which occurs more quickly in a growing microtubule, GTP hydrolyis or polymerization

Back 32

polymerization

Front 33

when GDP is present, which process is more favorable, polymerization or depolymerization?

Back 33

depolymerization

Front 34

what is the term used when a microtubule filament switches from growth to shrinking?

Back 34

catastrophe

Front 35

how many centrioles compose a centrosome?

Back 35

2

Front 36

which type of tubublin binds microtubules to the centrosome?

Back 36

gamma tubulin

Front 37

what is the energy source for kinesin and dynein?

Back 37

ATP

Front 38

is dynein transport typically anterograde or retrograde? kinesin transport?

Back 38

retrograde; anterograde

Front 39

name 6 different intermediate filaments and their locations.

Back 39

1) Keratins (epithelia)
2) Vimentins (CT, mesenchyme)
3) Desmin (skeletal muscle)
4) Glial Fibrillary Acid Protein (Glial cells)
5) Neurofilaments (neurons)
6) Lamins (nucleus of all cells)