Cytoskeleton

Question 1

Components of the Cytoskeleton

Answer 1

Actin filaments, microtubules, intermediate
filaments

Question 2

provide rigidity and structural stability to cells

Answer 2

Intermediate Filaments

Question 3

serve as part of a transport system in the cell and help to position organelles in the cell

Answer 3

Microtubules

Question 4

transport cargo throughout the cell through interaction with microtubules

Answer 4

Motor proteins

Question 5

A dense network of protein polymers that controls the shape and biochemical activity in the cell

Answer 5

cytoskeleton

Question 6

Structure of Intermediate Filaments

Answer 6

string and rope-like

Question 7

Intermediate Filaments form a strong durable network in the cytoplasm of the cell (T or F)

Answer 7

True

Question 8

A mutant from of keratin (an intermediate filament) makes skin blister easily (T or F)

Answer 8

True

Question 9

What do intermediate filaments do to the nuclear envelope?

Answer 9

support and strengthen it

Question 10

Microtubules grow out from what?

Answer 10

an organizing center

Question 11

Structure of Microtubules

Answer 11

hollow tubes made up of tubulin subunits

Question 12

Tubulin polymerizes from nucleation sites on a centrosome (T or F)

Answer 12

True

Question 12

What does GTP hydrolysis control?

Answer 12

the dynamic instability of mircotubules

Question 13

Microtubules guide the transport of molecules and molecular complexes in the nerve axon (T or F)

Answer 13

True

Question 14

What two molecular motors move along mircotubules?

Answer 14

kinesins and dyneins

Question 15

The same motor protein transports different types of cargo along the microtubules (T or F)

Answer 15

False, different motor proteins

Question 16

Structure of Actin Filaments

Answer 16

thin, flexible protein threads

Question 17

Actin filaments allow animal cells to do what?

Answer 17

take on many shapes and have many functions

Question 18

What decreases the stability of the actin polymer?

Answer 18

ATP hydrolysis

Question 18

In what component of the cytoskeleton does treadmilling occur?

Answer 18

actin filaments

Question 19

In what component of the cytoskeleton does dynamic instability occur?

Answer 19

microtubules

Question 20

Describe Treadmilling

Answer 20

Actins are being added to the plus end while actins fall off the minus end

Question 21

Describe Dynamic Instability

Answer 21

There is a GTP cap on plus end. GTP-tubulin is added to plus end causing the cap to be lost. The GDP-tubulin is all lost falling off the plus end. Once small, the GTP cap is reestablished.

Question 22

control the action of actin filaments in vertebrate cells

Answer 22

actin-binding proteins

Question 23

Forces generated by actin filaments in the cortex of the cell help move cell forward (T or F)

Answer 23

True

Question 24

What pushes the leading edge of a lampellipodium forward?

Answer 24

a web of polymerizing actin filaments

Question 25

a motor protein that functions with actin filaments

Answer 25

Myosin-I

Question 26

Myosin-II molecules can associate with one another to form myosin-II filaments (T or F)

Answer 26

True

Question 27

Bipolar myosin-II filaments can’t slide two actin filaments past each other (T or F)

Answer 27

False, they can

Question 28

How do muscles contract?

Answer 28

a sliding-filament mechanism