Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BMB 252 Mol/Cell Bio 2 > Exam 1: Quiz 2 - Chp 16 > Flashcards

Exam 1: Quiz 2 - Chp 16 Flashcards

The Cytoskeleton (48 cards)

Start Studying
1
Q

Which filaments resist stretching and provide mechanical strength for the cell?

A

Intermediate filaments

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

What are the three main functions of microtubules?

A

1) determine organelle position
2) direct intracellular transport
3) form miotic spindle

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

What are the three main functions of actin filament?

A

1) determine shape of cell
2) necessary for whole cell locomotion
3) drives pinching of one cell into two

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

What structure do miotic spindles assume outside of cell division?

A

attached to a centrosome and form a highway network in the cells

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

What is a protofilament?

A

one strand of tubulin dimers

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

What are the subunits of microtubules?

A

tubulin

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

How many protofilaments lay parallel to make a microtubule?

A

13

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

What is cell polarity? How is it determined?

A

one end of the cell is distinct from the other: cytoskeleton organization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why do protofilaments prefer to assemble together?

A

more filaments are more thermally stable because it takes more energy to break a greater number of bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the function of accessory proteins?

A

to control spatial distribution and dynamic behavior of filaments and convert information from signal pathways into cytoskeletal action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the function of moto proteins>

A

use ATP to move along filaments and carry cargo or cause filament sliding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What subunits make up actin?

A

actin

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

What gives actin filaments polarity?

A

the direction of the plus and minus ends of the actin subunits

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

What is the lag phase?

A

nucleation phase - actin subunits associate and disassociate and grow cannot begin

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

What is the growth phase?

A

elongation phase - oligomer serves as nucleation seed and actin filament beings to grow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the equilibrium phase?

A

steady state where filament has subunits associating and disassociating at equal rates

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

What end of an actin filament is it easier for subunits to bind to?

A

the plus end

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

Why is it easier for actin subunits to bind to the plus end?

A

adding subunits to minus end requires subunit to undergo confirmational change that a plus end subunit has already undergone

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

What happens to ATP on an subunit that has bound to an actin filament?

A

after a period of time, it is hydrolyzed

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

What is an ATP-cap?

Study These Flashcards
A

T-actin subunits at one end of a filament prevents subunit disassociation

21
Q

What is treadmilling?

Study These Flashcards
A

Hydrolysis lags behind plus end and catches up to minus end causing subunit to associate at the plus end and disassociate at the minus end at the same rate; filament stays the same length

22
Q

What does thymosin do>

Study These Flashcards
A

holds onto actin monomers to prevent addition to a filament

23
Q

What does profilin do?

Study These Flashcards
A

holds onto actin monomers and promotes polymerization

24
Q

What is the function of Arp 2/3 complex?

Study These Flashcards
A

serve as a nucleation seed and bind to side of existing filaments to promote branching

25
What end does the Arp 2/3 complex bind to?
the minus end
26
What is the function of formin?
Creates parallel bundles and prevents polymerization by reaching out and grabbing actin subunits from profilin
27
What are side binding proteins and their function?
bind of the sides of filaments; modulate interactions with other proteins and stabilize/stiffen actin filaments
28
What are capping proteins and their function?
bind on the end of filaments; stabilize them
29
What do severing proteins do?
break filaments into smaller pieces with new filament ends to facilitate dynamic movement
30
What is the function of proteins in the Gelsolin superfamily?
interact with the sides of filaments to cut in the middle of D-subunits
31
What is a D-actin monomer?
Actin subunit containing ADP
32
What is a T-actin monomer?
Actin subunit containing ATP
33
What does cofilin do?
binds along ADP-bound filaments and twists to weaken them; causes filament to break
34
What does fimbrin do?
forms tightly packed parallel bundles of alpha actin filaments; prevents myosin II from entering
35
What does alpha-actinin do?
forms loose actin bundles which allow myosin II to enter
36
What is the structure of a myosin heavy chain?
globular N-terminal head domain and long alpha-helix tail that dimerizes with another heavy chain to form a coiled coil
37
What is the structure of a myosin light chain?
short and binds close to the N-terminal head domain
38
What are thick filaments?
bipolar filaments of myosin with hundreds of myosin heads oriented in opposite directions
39
What direction do thick filaments walk?
towards the plus end of actin filaments
40
Describe the attached position of a myosin head
myosin head is tightly attached to actin filament and no ATP is bound
41
Describe the released position of a myosin head
ATP binds to large cleft on the back of the myosin head and myosin releases from actin
42
Describe the cocked position of a myosin head
1) Cleft on the back of the myosin head closes around ATP 2) Movement in lever arm displaces myosin head ATP is hydrolyzed (ADP and Pi remain bound)
43
Describe the force generation a myosin head
1) myosin head is weakly bound to a new site on actin (facilitated by energy from hydrolysis) 2) Pi is released, and myosin-actin bond is tightened 3) power stroke occurs that moves actin filament and releases ADP
44
What is rigor position of a myosin head?
same position as attached, cause of rigor mortis
45
What is the Z-disc?
capZ proteins cap plus ends of actin filaments and associate to form Z-disc
46
What dies tropomodulin do?
binds to minus end of actin filaments to prevent ADP subunits from disaasociating
47
What does nebulin do?
stabilize actin polymers in sarcomeres by wrapping around them
48
Why does an increase in muscle cell cytosolic Ca2+ cause contraction?
interacts with troponin which moves tropomyosin away from myosin binding sites on actin

BMB 252 Mol/Cell Bio 2 (9 decks)

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