The Cytoskeleton: Part 2 Flashcards Preview

Biology > The Cytoskeleton: Part 2 > Flashcards

Flashcards in The Cytoskeleton: Part 2 Deck (36):
1

The dynein motor protein complex is a ______ _____ that moves towards the _____ end

microtubule motor
minus

2

What is dynein?

a large protein complex; associated with other protein complexes that together transport cargo along microtubules

3

Dynein uses ATP to...

move along the microtubule

4

What is the difference between dynein movement and kinesin movement?

dynein movement: towards the cell body (minus end)
kinesin movement: towards the axon terminus (plus end)

5

What three processes are microfilaments/actin filaments involved in?

1. cell motility
2. contractile activity
3. cytokinesis

6

What are microfilaments made of? (five things, including shape and structure)

1. actin monomers
2. flexible
3. inextensible
4. helical filaments
5. two protofilaments

7

Myosin is a ____ _____

motor protein

8

Microfilaments are composed of a single type of _____ protein.

globular

9

Are actin filaments polar? Why or why not?

yes; due to the regular orientation of actin monomers in each protofilament

10

Which end is the tail? Head? (plus or minus)

head-plus
tail-minus

11

Free monomers are bound to _____ which is bound in the _____ of the protein

ATP
centre

12

What is actin?

ATPase; hydrolyzes ATP

13

ATP hydrolysis occurs more rapidly after...

actin monomers have been incorporated into the filament

14

Growth of the filament is faster at the _____ end; actin filaments have an _____ _____

plus
ATP cap

15

What is actin filament treadmilling?

-although an actin filament looks stable, there is continual exchange of monomers at the ends
-occurs at a very specific concentration range

16

What occurs at each end at the treadmilling concentration?

plus end: net addition
minus end: net loss

17

The ____ end has a higher affinity for actin monomers than the ____ end

plus
minus

18

Myosin has tails of...

the two heavy chains organized in a coiled-coil (of alpha-helices)

19

Heads of the heavy chain are associated with four _____ _____

light chains (2 at each head)

20

ATP is hydrolyzed by the myosin head or tail?

head

21

Myosin is a family of

related proteins

22

What kind of domains are conserved within the myosin family?

motor

23

What is myosin II?

skeletal muscle

24

The _____ of myosin II along actin filaments causes muscles to _____

sliding
contract

25

Myosin is a _____ filament. Actin is a _____ filament

thick
thin

26

Describe the myosin/muscle cell contractile apparatus.

1. myosin attached to an actin filament
2. ATP binding releases myosin from actin
3. ATP hydrolysis occurs along with a conformational change that displaces the myosin head
4. myosin binding to actin releases the Pi triggering the force-generating shape change
5. At the end of the cycle myosin is in the initial conformation but has moved to a new position in the actin filament

27

What is the main actin motor protein?

myosin II, plus end directed

28

What are the two microtubule motor proteins?

dynein, minus end directed
kinesin, plus end directed

29

What are two common mechanisms of motor proteins?

1. they all couple ATP hydrolysis with conformational changes to generate force
2. all move in a specific direction along filaments that have polarity (plus/minus end)

30

Intermediate filaments are involved in what kind of support?

structural

31

Intermediate filaments are not found in _____ and _____

plants and animals

32

A coiled-coil dimer forms a staggered antiparallel tetramer and has no...

no filament polarity and no known motor proteins

33

What is a tetramer?

soluble form of a coiled coil dimer (staggered)

34

Intermediate filaments are prominent in cells subjected to mechanical stress including... (3 types of cells)

1. epithelial cells - keratin
2. neurons - neurofilament proteins
3. muscle cells - desmin

35

Filaments in epithelial cells are anchored at sites of ____-____ contact by ______. It also involves _____ strength.

cell-cell
desmosomes
mechanical

36

Are intermediate filaments extensible or inextensible?

Extensible