Lec 18

Question 1

Cytoskeleton

Answer 1

Enormous protein filaments made of chains of globular proteins and bundles of fibrous proteins

Question 2

Microtubules is made up of

Answer 2

Subunit protein- Tubulin

Protein filament- Microtubules

Question 3

Tubulin is made up of

Answer 3

Polypeptides

Question 4

Tubulin connects to make a

Answer 4

Protofilament

Question 5

Protofilaments combines to form

Answer 5

Microtubules

Question 6

Polypeptides are made by

Answer 6

Different genes on different chromosomes

Question 7

Protofilaments can be arranged in bundles known as

Answer 7

Singlets

Doublets

Triplets

Question 8

Microtubule polarity

Answer 8

There is a + and - end that is not due to charge

+ means active

Question 9

Assembly and disassembly of microtubules

Answer 9

Tubulins are added and removed from the plus end

Question 10

Microtubules are connected to

Answer 10

Centrosomes

Question 11

Centrosomes are a

Answer 11

Ball of proteins

Question 12

How is the negative end of the microtubule connected to the centrosome

Answer 12

With a Gamma Tubulin Ring Complex

Question 13

Microtubules outside the cell

Answer 13

Remain active outside the cell

Question 14

Microtubules grow and shrink

Answer 14

Independently of their neighbors

Question 15

Tubulin is regulated by

Answer 15

GTP

Question 16

Both tubulin polypeptides on microtubules contain

Answer 16

Nucleotides

One is accessible by GTP or GDP

The other is inaccessible and is always GTP

Question 17

D form

Microtubules

Answer 17

GDP and GTP

Inactive form that forms curved protofilaments

Question 18

T form

Microtubules

Answer 18

GTP and GTP

Active form that forms straight protofilaments

Question 19

How to change from D to T form

Answer 19

Nucleotide replacement that occurs when in the cytosol

Hydrolysis occurs when part of a microtubule

Question 20

T form microfilament addition

Answer 20

Protofilaments are added in the GTP active form

Even when the GTP is inactive, the protofilaments that are added are still straight

Question 21

D form microfilament removal

Answer 21

Protofilaments that are curved and in the inactive form fall off

Once they’re in the cytosol, nucleotide replacement happens which puts the protofilaments back into the T form

Question 22

Dynamic instability

Answer 22

Cells being unstable

It is desirable as it supports the cell

Question 23

Dynamic instability

Compression

Answer 23

Trying to crush the cell

Question 24

Dynamic instability

Tension

Answer 24

Trying to rip the cell

Question 25

Microtubules help cells resist

Answer 25

Compression

Question 26

Microtubules during prophase

Answer 26

Extend and contract to find the centromeres

Question 27

Once the microtubule contacts the centromere during prophase, it is stabilized by

Answer 27

Kinetochore proteins

Question 28

RBCs and microtubules

Answer 28

Disc shape due to ring of microtubules

Question 29

Neuron axons and microtubules

Answer 29

Axons are too long to have their microtubules connected to the centrosome They are instead stabilized by proteins called tau