Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

biochemistry > actin > Flashcards

actin Flashcards

1
Q

What are the main roles of the actin cytoskeleton?

A

Cell motility, contractility, shape changes, cytokinesis, cell polarity, phagocytosis, and macropinocytosis

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

What percentage of skeletal muscle mass is actin?

A

20%

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

What percentage of total proteins in non-muscle cells is actin?

A

5%

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

Describe the structure of actin proteins.

A

actin has 375 amino acids weighting 43kDa
globular actin (G-actin) monomers form double helical F actin

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

What are the three classes of actin isoforms?

A

Class 1: Non-muscle β, γ, and smooth muscle γ.
Class 2: Skeletal, cardiac, and vascular α-actin.
Class 3: Actin-RPV, centractin, and lower eukaryote actins.

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

What are transient actin structures?

A

Lamellipodia, filopodia, and ruffles.

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

What is a stable actin structure and its function?

A

microvilli
increases surface area for absorption

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

What are the two ends of an actin filament called?

A

barbed (-) end
pointed (+) end

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

Which end grows faster?

A

barbed end

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

What is actin treadmilling?

A

subunits are added at barbed end and removed at pointed end

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

Name three sources of new actin filaments.

A

de novo nucleation
uncapping of barbed end
severing of existing filaments

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

What does profilin do?

A

Binds ATP-actin, reduces critical concentration, and facilitates nucleotide exchange (ADP-actin → ATP-actin).

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

What is the function of thymosin-β4?

A

Sequesters G-actin to maintain a polymerization-ready pool

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

How do capping proteins regulate actin?

A

They cap the barbed-end to stop elongation.

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

Which proteins regulate actin dynamics?

A

Rho-family GTPases (Rho, Rac, Cdc42).

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

What is the function of Rac?

A

promotes lamellipodia formation

17
Q

What does Cdc42 regulate?

A

filopodia formation

18
Q

What is the Arp2/3 complex?

A

7 polypeptide complex that nucleates new actin filaments and from branches

19
Q

How is the Arp2/3 complex activated?

A

by WASP/scar proteins

20
Q

Name a pathogen that exploits actin and how.

A

listeria uses actin to form comet tails for intracellular movement

21
Q

What are the main actin structures in cell movement?

A

Lamellipodia (sheet-like), filopodia (finger-like), and stress fibers.

22
Q

What is the critical concentration at the barbed-end?

A

0.1 μM.

23
Q

What is the critical concentration at the pointed-end?

A

0.6 μM.

24
Q

What does filamin do?

A

create cross-linked actin networks

25
Q

What are ERM proteins?

A

Ezrin, Radixin, Moesin; they anchor actin to the plasma membrane.

biochemistry (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions