(Damjanovski) Lecture 6

Question 1

Microtubule purpose

Answer 1

Vesicle transport (bi-directional)

Question 2

What do motor proteins in microtubules require?

Answer 2

ATP

Question 3

Kinesin

Answer 3

(+) end directed motor proteins
* On microtubules

Question 4

Kinesin general structure

Answer 4

• 2 heavy chains (Head, neck and tail)
  2 light chains (variable)

Question 5

Kinesin light chain purpose

Answer 5

Recognize cargo

Question 6

Types of kinesin we have to know

Answer 6

1. Kinesin-1
2. Kinesin-2
3. Kinesin-5
4. Kinesin-13

Question 7

Kinesin 1 purpose

Answer 7

Organelle transport

Question 8

Kinesin 1 structure

Answer 8

4 proteins
* 2 heavy chain
2 light chain

Question 9

Kinesin 2 purpose

Answer 9

Organelle transport

Question 10

Kinesin 2 structure

Answer 10

3 proteins
* 2 Heavy chain
* 1 Light chain

Proteins are different (heterotrimeric)

Question 11

Kinesin 5 purpose

Answer 11

Sliding of microtubules

Question 12

Kinesin 5 structure

Answer 12

No tail
* 4 heavy chains

No tail means no cargo

Question 13

Kinesin 13 purpose

Answer 13

End disassembly

Question 14

Kinesin-13 structure

Answer 14

2 heavy chains

Special (only head and neck)

Question 15

Where does kinesin 13 end disassembly usually occur?

Answer 15

(+) end

Question 16

Where is kinesin directed movement directed?

Answer 16

Anterograde
* Toward cell surface

Question 17

How much do kinesin heads move when ATP is hydrolyzed?

Answer 17

16 nm

Question 18

Dynein

Answer 18

(-) end directed movement
* On microtubules

Question 19

Where is dynein directed movement directed to?

Answer 19

Retrograde
* Towards cell center

Question 20

Dynein structure

Answer 20

Heavy chain (head, neck and tail)

Question 21

What connects dynein to the microtubule?

Answer 21

The heavy chain/head region

Question 22

What specific area of the head domain binds to the microtubule in dynein?

Answer 22

Stalk

Question 23

What is required for dynein directed movement?

Answer 23

ATP hydrolysis
* Dynein head domain has ATPase activity

Question 24

Dynactin

Answer 24

Complex that links dynein to cargo and regulates movement

Question 25

Does dynein have a light chain?

Answer 25

No * Needs dynactin to link to cargo

Question 26

What regulates dynactin?

Answer 26

Dynamitin

Question 27

Along with dynactin, what binds to the microtubule to provide stability to the cargo in dynein transport?

Answer 27

P150

Question 28

Does P150 use ATP?

Answer 28

No

Question 29

Cilia vs. Flagella

Answer 29

Same thing * Cilia is small, many, sweeps things across tissue * Flagella is few and propel cells

Question 30

What is the underlying structure of cilia and flagella?

Answer 30

Axoneme

Question 31

What is the common array of microtubules in axonemes?

Answer 31

9 doublets + 2 singlets

Question 32

What connects the microtubules together in an axoneme?

Answer 32

Nexin

Question 33

Microtubule types in basal body

Answer 33

Triplet microtubules

Question 34

What happens in the transitional zone in basal bodies and cilia/flagella?

Answer 34

The triplet microtubules become doublet microtubles * The singlet microtubules in the middle are not present

Question 35

How are basal bodies different from centrioles?

Answer 35

Basal bodies polymerize tubules directly (doesn't require periocentriolar matrix)

Question 36

What is axonmeal bending powered by?

Answer 36

Axonemal dynein * IMPORTANT: REMEMBER THE AXONEMAL PORTION

Question 37

What is critical for axoneme bending?

Answer 37

Nexin

Question 38

Do all the dynein in axoneme bending slide at the same time?

Answer 38

Not all bind and slide at the same time

Question 39

What is utilized in intraflagellar transport?

Answer 39

CYTOPLASMIC dynein

Question 40

Intraflagellar transport moves material...

Answer 40

Up and down

Question 41

How are primary cilia different?

Answer 41

1. Non-motile 2. No axonemal dynein 3. Not found in mitotic cells

Question 42

What are non-motile primary cilium used for?

Answer 42

Cell-cell signaling

Question 43

Microtubules in Interphase

Answer 43

Centrosome duplication

Question 44

Microtubules in Prophase

Answer 44

Breakdown of interphase microtubule array * Replace by mitotic asters * Mitotic aster separation

Question 45

Microtubules in prometaphase

Answer 45

Chromosome captured + orientated Brought to spindle equator

Question 46

Microtubules in metaphase

Answer 46

Chromosomes aligned at metaphase plate

Question 47

Microtubules in anaphase

Answer 47

Anaphase A * Chromosomes move to poles Anaphase B * Spindle pole separation

Question 48

Microtubules in telophase

Answer 48

Assembly of contractile ring

Question 49

What MTOC is present in mitosis?

Answer 49

Spindle poles

Question 50

Why does microtubule stability drop during mitosis?

Answer 50

Prevents large amount of errors in DNA

Question 51

What microtubules make up the spindle?

Answer 51

Polar microtubules Kinetochore microtubules

Question 52

What microtubules make up the mitotic apparatus?

Answer 52

Polar microtubules Kinetochore microtubules Astral microtubules

Question 53

What mediates chromosome attachment to microtubules?

Answer 53

Kinetochore proteins

Question 54

What is the attachment site for microtubules on chromosomes?

Answer 54

Centromere

Question 55

Does the microtubule ever actually touch the centromere?

Answer 55

No

Question 56

What are key things that are required in spindle formation?

Answer 56

* ALL chromosomes must be captured * ALL must be aligned during metaphase * Requires motors and microtubule dynamics

Question 57

What is responsible for attachment of microtubule to centromere?

Answer 57

Kinesin 7

Question 58

What is responsible for microtubule depolymerization and pulling the chromosomes?

Answer 58

* Dynein * Kinesin 13 * Kinesin 4

Question 59

What assures the bi orientation (that chromosome is attached to both spindle poles)?

Answer 59

Tension

Question 60

Why are microubule interactions with the kinetochore weak when there is no tension?

Answer 60

Phosphorylation of Ndc80 proteins at kinetochore

Question 61

What phosphorylates Ndc80 proteins at the kinetochore?

Answer 61

Aurora B

Question 62

When and what happens when Aurora B stops phosphorylating Ndc80?

Answer 62

When there is tension * Ndc remains bound to the microtubule

Question 63

When does tension occur?

Answer 63

When the centromere is captured from both sides by microtubules

Question 64

What centers/orientates the spindle?

Answer 64

Dynein-dynactin center

Question 65

What contains the dynein-dynactin center that pulls astral microtubules to orient the spindle?

Answer 65

Cortical anchor * Must be active to allow movement in that direction

Question 66

Anaphase A

Answer 66

Chromosomes moving to poles * requires microtubule shortening

Question 67

Anaphase B

Answer 67

Pole separation * Requires motor proteins

Question 68

What proteins are involved in Anaphase A?

Answer 68

Kinesin 13

Question 69

What proteins are involved in anaphase B

Answer 69

Dynein Kinesin-5

Question 70

Polar microtubules help localize...

Answer 70

RhoGTP

Question 71

Where does RhoGTP localize?

Answer 71

Metaphase plate

Question 72

What does RhoGTP allow for?

Answer 72

Formation of contractile actin/myosin ring