Test 2 Cytoskeleton

Question 1

T/F: A cell can change its shape using its cytoskeleton.

Answer 1

True

Question 2

Where is actin found?

Answer 2

Toward the periphery of the cell.

Question 3

What are the intermediate filaments of the cell?

Answer 3

Actin and tubulin. They build a network within the cell.

Question 4

T/F: The cytoskeleton determines cellular organization and polarity.

Answer 4

True

Question 5

What are the 3 different filaments that compose the cytoskeleton?

Answer 5

Actin filaments, intermediate filaments and microtubules.

Question 6

What is the structure of microtubules?

Answer 6

Hollow cylindrical structures built from protofilaments composed of alpha-tubulin heterodimers stacked head to tail and folded into a tube.

Question 7

What is protofilaments?

Answer 7

Tubulin subunits composed of alternating alpha-tubulin and beta-tubulin.

Question 8

What happens to GTP at the GTP binding site of alpha-tubulin?

Answer 8

GTP is trapped, it is never hydrolyzed nor exchanged.

Question 9

What happens to GTP at the GTP binding site of beta-tubulin?

Answer 9

GTP is hydrolyzed.

Question 10

What is dynamic instability?

Answer 10

Influences by the binding and hydrolysis of GTP on the beta-subunit of the tubulin dimer. Addition of GTP allows the protofilament/microtubule to grow, while GTP hydrolysis creates the protofilament/microtubule to shrink.

Question 11

What is the MTOC?

Answer 11

Microtubule organizing center: where microtubules originate.

Question 12

What are the (2) motor-proteins associated with microtubules?

Answer 12

Kinesin and dynein.

Question 13

Toward which end does kinesin travel on the microtubule?

Answer 13

Toward the plus end.

Question 14

Toward which end does dynein travel on the microtubule?

Answer 14

Toward the minus end.

Question 15

What is the purpose of MAPs?

Answer 15

Moving organelles and vesicles in the cell.

Question 16

What are flagella used for?

Answer 16

Movement of cells in a liquid environment.

Question 17

T/F: Cilia can move fluid above a cell.

Answer 17

True

Question 18

What is the structure of an actin filament?

Answer 18

Consists of (2) parallel protofilaments, which is a flexible helical structure. Has a plus and minus end.

Question 19

What is the function of intermediate filaments?

Answer 19

Maintenance of cell shape, organelle attachment, and formation of the nuclear lamina. Example: Keratin

Question 20

What is the function of actin microfilaments?

Answer 20

Maintenance of cell shape, changes of the cell shape, muscle contraction, and cell movement.

Question 21

What is the function of tubulin microtubules?

Answer 21

Maintenance of cell shape, cell movement, chromosome movement during cell division, and movement of organelles.

Question 22

Where are actin microfilaments found within the cell?

Answer 22

In the periphery of the cell, sometime running parallel.

Question 23

Where are tubulin microtubules found within the cell?

Answer 23

Coming from an organizing center and spreading towards the cell periphery. Example: centrosomes.

Question 24

Where are intermediary filaments found within the cell?

Answer 24

Distributed along the whole cytoplasm of the cell, building a network of filaments in the cytosol.

Question 25

What is the subunit for microfilaments?

Answer 25

Actin.

Question 26

What is the subunit for microtubules?

Answer 26

Tubulin (alpha and beta).

Question 27

What is the subunit for intermediary filaments?

Answer 27

Keratin, Lamin, and Vimentin.

Question 28

What is the structure of microfilaments?

Answer 28

Two helical crossed actin strands.

Question 29

What is the structure of microtubules?

Answer 29

Tubes of 11-18 strands per microtubule.