Lecture 5 Cytoskeleton

Question 1

What are the three “cytoskeletons”?

Answer 1

microtubules, microfilaments, and intermediate filaments

Question 2

Microtubules are made of ____ while microfilaments are made of _____

Answer 2

tubulin

actin

Question 3

Microtubules are often found in ____

Answer 3

golgi

Question 4

What are functions of the cytoskeleton? (3)

Answer 4

Maintain cell shape
stabilize cell adhesion and placement
facilitate movement

Question 5

Microtubules bind GTP at the _ (+/-) end, which promotes _____

Answer 5

+

polymerization

Question 6

_____ have GDP at their minus end, which favors dissociation.

Answer 6

Microtubules

Question 7

The minus end of a microtubule can embed in a ____, which is positioned near the nucleus

Answer 7

centrosome

Question 8

_____ create intracellular highways, providing transport for organelles and axons.

Answer 8

Microtubules

Question 9

____ act as motor proteins and move an organelle to the PLUS end of the microtubule

Answer 9

Kinesins

Question 10

Dyneins move organelles toward the _ end of a microtubule

Answer 10

minus

Question 11

Dynesis and Kinesin are examples of ____ associated proteins and are involved in signal transduction as____

Answer 11

microtubule

kinases

Question 12

Blockading the movement of MTOC’s towards poles during prophase is a target of ____

Answer 12

chemotherapy

Question 13

Cilia are made up of ____

Answer 13

microtubules

Question 14

Microfilaments consist of _____ filaments and require _____ to polymerize

Answer 14

actin

ATP

Question 15

Microfilaments are _____ stable than microtubules

Answer 15

more

Question 16

_____ is when there is turnover of microfilaments without change in size.

Answer 16

Treadmilling

Question 17

Actins stabilize ____ adhesions in stress fibers

Answer 17

integrin

Question 18

____ belts consist of circumferential actin near apical cell surface

Answer 18

adhesion

Question 19

Actin stabilizes ____-mediated adherens junctions and is organized by _____

Answer 19

cadherin

catenin

Question 20

______ is an outward projection of the cytoplasm in the leading edge of migrating cells that is made of actin

Answer 20

lamellapoida

Question 21

The cleavage furrow is an invagination of cell surface during cytokinesis that is organized by the ______ cytoskeleton

Answer 21

actin

Question 22

Microvilli are fingerlike extensions at the cell surface made of ____ filaments

Answer 22

actin

Question 23

____ is a mushroom poison that binds F-actin and prevents disassembly at the minus end

Answer 23

Phalloidin.

Question 24

Cytochalasins are alkaloid fungal toxins that bind to the ____ of actin and block polymerization

Answer 24

plus

Question 25

Latrunculins bind ____ and induce depolymerization

Answer 25

G-actin

Question 26

_____ creates a membrane skeleton and is most common in erythrocytes. Sickle cell anemia is caused by a modification of it

Answer 26

Spectrin

Question 27

______ _____ are very stable, with assembly and disassembly being regulated by protein phosphorylation

Answer 27

intermediate filaments

Question 28

Type _ intermediate filaments are acid keratins. Type _ are neutral to basic keratins

Answer 28

1, 2

Question 29

Change in _____ expression is among the most common markers of neoplasia

Answer 29

cytokeratins (ie, type 1 and 2 IFs)

Question 30

Vimentin and Desmin are examples of type 3 ____ _____’s

Answer 30

intermediate filaments

Question 31

_____ is a type 3 IF used as a marker of dedifferentiation of invasive carcinomas

Answer 31

Vimentin

Question 32

_____ is found in skeletal muscle at the Z-disk.

Answer 32

Desmin

Question 33

Type __ intermediate filaments are neurofilaments; common in axons and dendrites

Answer 33

4

Question 34

Intermediate filaments are ropelike fibers of _____, _____, or ______

Answer 34

keratins
lamins
vimentin

Question 35

A _______ is a vertical linear array of alpha/beta tubulin dimbers

Answer 35

protofilament

Question 36

_ protofilaments associate to form a tubule in microtubules

Answer 36

13

Question 37

Taxol is an anti-cancer drug that binds to ____, preventing their depolymerization

Answer 37

mictrotubules

Question 38

Actin bundles along basal cell surfaces terminate at ____ adhesions

Answer 38

focal

Question 39

Actin is organized by _-actinin and _____ in stress fibers

Answer 39

alpha, talin

Question 40

Hereditary spherocytosis is due to mutant _____

Answer 40

spectrin

Question 41

alpha-______ is a type 4 neurofilament found in the spinal chord

Answer 41

internexin