Microtubule section 1

Question 1

Both actin and microtubules frequently disassemble and reassemble as the result of a stimulus

Answer 1

Intermediate filaments don’t do so as much

Question 2

Why is it better for proteins to form multimeric filaments?

Answer 2

The multimer is thermodynamically stable, won’t just break apart. It will also assemble a bond at a time at the end instead of breaking multiple bonds

Question 3

What are microtubules made out of?

Answer 3

Tubulin

Question 4

What is the difference between alpha and beta tubulin?

Answer 4

beta tubulin can hydrolyze GTP. The Beta end is positive. The microtubule is built towards the plus end of the microtubule.

Question 5

How does the microtubule resist being hydrolyzed?

Answer 5

It forms an ATP cap on actin and a GTP cap on Microtubules

Question 6

How does a GTP cap on the plus end stabilize microtubules?

Answer 6

It straightens the microtubule and it forms stronger lateral bonding

Question 7

which subunit is the GTP cap binding too? is it capable of binding to all of this subunit?

Answer 7

The beta subunit. Yes GTP GDP binding is seen for ALL Beta subunits

Question 8

Does the GTP cap bind to all beta subunits?

Answer 8

All those at the top/plus end of the protein. Maybe the top 15 for each column

Question 9

When GTP is bound to beta subunit? GDP?

Answer 9

straight stable

curved unstable

Question 10

How much faster does microtubule depolymerization occur if the microtubule has a GDP cap vs a GTP cap?

Answer 10

the microtubule breaks down 100x faster

Question 11

What does dynamic instability refer to?

Answer 11

How microtubules switch from periods of slow growth to rapidly shrinking

Question 12

Which end of a microtubule grows faster?

Answer 12

The plus end

Question 13

What is treadmilling (in microtubules)?

Answer 13

When the plus end grows at roughly the rate that the minus end shrinks

Question 14

What causes dynamic instability?

Answer 14

Loss and recovery of GTP cap.

Question 15

each MT grows and shrinks _____ of other MTs.

Answer 15

independently

Question 16

Catastrophe refers to?

Answer 16

The rapid loss of alpha and beta tubulin which occurs in the absence of the GTP cap.

Question 17

Rescue refers to?

Answer 17

When a microtubule in catastrophe regains its GTP cap and starts growing again.

Question 18

Taxol come from where

Answer 18

The Pacific Yew

Question 19

The drug produced from taxol is called

Answer 19

Paclitaxel

Question 20

The mechanism by which taxol affects cancer is?

Answer 20

polymerizes microtubules

Question 21

Colchicine comes from where?

Answer 21

The Coleus plant

Question 22

The mechanism by which colchicine acts is?

Answer 22

It depolarizes microtubules.

Question 23

The drug produced from colchicine is called

Answer 23

Oryzalin, it is a herbacide

Question 24

What is the difference between gamma tubulin and and gamma turc?

Answer 24

gamma tubulin is a modified form of tubulin protein. It is found on the edge of gamma TuRC complex which attaches to the end of the alpha tubulin. It looks like a lock washer

Question 25

Where are gamma TuRC complexes generally found.

Answer 25

in the pericentriolar material (next to the centrioles).

Question 26

Which side of the tubulin attaches to the gamma turc complex

Answer 26

Alpha/negative

Question 27

What is the structure of a centriole?

Answer 27

9-3 structure, inner microtubule is complete

Question 28

Distal appendages occur only on…

Answer 28

The mother centriole

Question 29

How many SAS-6 dimers are within a centriole?

Answer 29

9, one for each of the 9-3 microtubules