Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

My Packs: (WIZEPREP) (BIO 2382) > Chapter 4: 4.2 Motor Proteins > Flashcards

Chapter 4: 4.2 Motor Proteins Flashcards

1
Q

Define:

Motor proteins

A

A class of proteins capable of moving along a surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do motor proteins do in a cell?

A
  • Move along components of the cytoskeleton
  • Transport cellular components throughout the cytoplasm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where does the energy for movement of motor proteins come from?

A

ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give examples of motor proteins

A
  • Kinesin
  • Myosin
  • Dynein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define:

Kinesin

A

Moves along microtubules in the (+) direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define:

Myosin

A

Moves along actin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define:

Dynein

A

Moves along microtubules in the (-) direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the three types of movement?

A
  1. Motor proteins “walk” along the cytoskeleton transporting cargo
  2. Motor proteins cause a filament to move
  3. Motor proteins cause a “bend”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe:

How motor proteins “walk” along the cytoskeleton transporting cargo

(3 points)

A
  • Head proteins attach to the cytoskeleton
  • Tail proteins attacch to the cargo
  • The head proteins alternate attaching and detaching from the cytoskeleton, taking “steps” forward every time they re-attach
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe:

How motor proteins cause a filament to move

(3 points)

A
  • Head proteins attach to a filament (e.g. actin filament)
  • Tail proteins are anchored to a surface
  • As the head proteins carry out “walking motion”, the tail remains anchored. The head proteins therefore push the filament along, causing it to move
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe:

How motor proteins cause a “bend”

A
  • Tails attached to one microtubule
  • Heads attach to another microtubule
  • The two microtubules are held together by a linking protein
  • As the heads carry out their “walking” motion, it causes a bend to form
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are myosins?

A

A family of actin-binding motor proteins that hydrolyze ATP to move along actin filaments towards the plus end of actin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define:

Myosin I

A

Monomeric form of myosin involved in movement of vesicles and microfilaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does Myosin I move?

A

Moves along a microfilament in a repetitive cycle of binding, detachment, and re-binding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe:

Myosin I

A
  • Single globular ATPase head domain (binds actin microfilament)
  • Single tail domain (binds cargo)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define:

Myosin II

A

Form of myosin involved in muscle contraction and cell movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Myosin II is a dimer, meaning that…

A

Two globular ATPase head domains; tails coiled around each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define:

Myosin filament

(In Myosin II)

A

A bipolar filament made from clusters of myosin II molecules bound together by the tail region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Define:

Myofibrils

A

Contractile elements of skeletal muscle fibres, organized into sarcomeres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a sarcomere?

A

A contractile unit of a skeletal muscle fibre
* Consists of myosin filaments and actin filaments

21
Q

In sarcomeres:

What are myosin and actin filaments also known as?

A
  • Thick filaments (Myosin filaments)
  • Thin filaments (Actin filaments
22
Q

Describe:

Movement produced by sarcomeres

A

Simulatneous shortening of every sarcomere in a cell results in contraction

23
Q

What happens to myosin heads when a muscle is stimulated to contract?

A

The myosin heads walk along the actin filament in repeated cycles of attachement and detachment

24
Q

What is the cycle that myosin heads undergo during muscle movement?

A
  • Attached
  • Released
  • Cocked
  • Force-Generating
  • Attached
25
Initially, the myosin head is...
Attached to an actin microfilament
26
# In the released state: What happens?
Myosin head binds to ATP, reducing its affinity for the actin microfilament
27
# In the cocked state: What happens?
ATP hydrolysis * ADP + phosphate * Causes conformational changes that move the myosin head toward the plus end of the actin microfilaments
28
# In the force-generating stage: What happens?
Myosin heads (currently bound to ADP) binds weakly to actin, causing release of the phosphate produced from ATP hydrolysis
29
What occurs between the force-generating stage and attached stage?
Power stroke
30
# Define: Power stroke
Myosin head releases the ADP and binds actin tightly again, this time closer to the plus end
31
What happens when simultaneous power strokes from multiple myosins occur at once?
Brings the actin microfilaments of the sarcomere closer together
32
When multiple power strokes occur simultaneously, what happens to the sarcomere?
The sarcomere is shortened * Causes muscle contraction
33
What is the Sliding-Filament Theory?
Thick filaments (myosin) move past thin filaments (actin)
34
# In the Sliding-Filament Theory: 1. What happens to the sarcomeres? 2. What happens to the filaments?
1. Sarcomeres shorten 2. Filaments remain same length
35
# In the Sliding-Filament Theory: What does this theory require?
* Actin-myosin binding sites * ATP * Ca2+
36
What is the role of Ca2+ in muscle contraction?
Allows for **myosin binding** on **actin**, by shifting the troponin-tropomyosin complex
37
When does the Actin-Myosin ATP Cycle begin?
Begins as the myosin head is ready to bind actin once it has hydrolyzed ATP
38
What are the steps of the Actin-Myosin ATP Cycle?
1. Phosphate is released (now, strong bond between actin and myosin is able to form) 2. Power stroke happens 3. ADP is released
39
What is the strong bond between actin and myosin formed called?
Cross-bridge
40
After the actin-myosin ATP cycle, what state is the muscle in?
Contracted state
41
How does the muscle get back into relaxed state?
ATP binds myosin again, causes release of actin
42
# Explain: What happens in rigor mortis?
Due to the lack of ATP, the muscles are unable to relax
43
How long does the Actin-Myosin ATP Cycle continue for?
Will continue as long as Ca2+ and ATP are available
44
What are cilia and flagella comprised of? How do they move?
* Composed largely of microtubules * Move through the action of **dynein**
45
# State: The microtubule arrangement of cilia + flagella
9 + 2 arrangement * 9 fused pairs of microtubules surrounding 2 central microtubules
46
# Define: Cilia
Hair-like structures that protrude from the plasma membrane of many eukaryotic cells (e.g. cells in the small intestine)
47
# Describe: How cilia move
Beat in a whip-like fashion to move fluid across the cell surface * Some protists use cilia for locomotion
48
# Describe: Flagella
Similar in structure to cilia, but longer * Main role is in locomotion
49
# List: The differences between cilia and flagella | (5 points)
Cilia * Eukaryotes * Short, hair-like * Wave-like movement * Many per cell Flagella * Eukaryotes and Prokaryotes * Long, thread-like * Rotational movement * Few (<10) per cell

My Packs: (WIZEPREP) (BIO 2382) (27 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions