Cytoskeleton & Response to Mechanical Stress Flashcards Preview

Physiology Exam 3 > Cytoskeleton & Response to Mechanical Stress > Flashcards

Flashcards in Cytoskeleton & Response to Mechanical Stress Deck (57):
1

Cytosol

Inside of cell → surrounds organelles

2

Cytoskeleton is a complex network of?

It extends through ____ and attaches to?

Complex network of interconnected filaments and tubules → extends throughout cytosol, attaches to inner surface of plasma membrane

3

Cytoskeleton plays a role in:

1. Cell movement
2. Cell division
3. Internal organization (allows cell to assume shapes)
4. Cell signaling
5. Cell adhesion

4

Major structural elements of cytoskeleton

1. Microtubules
2. Microfilaments
3. Intermediate fibers

5

Microtubule diameter

25 nm (largest)

6

Microfilaments diameter

7 nm (smallest)

7

Intermediate filament diameter

8-13 nm

8

Ways that microtubules, microfilaments and intermediate filaments/fibers are unique to each other

1. Size
2. Structure
3. Intracellular distribution
4. Formed by polymerization of different proteins
5. Accessory proteins

9

Microtubule functions

1. Cellular movement (cilia, flagella)
2. Maintenance of nerves and axons
3. Spatial orientation in cytosol → govern location of organelles

10

Microtubules are cylinders. Tell me about their characteristics.

1. Hollow
2. Straight
3. Outer diameter = 25 nm, inner diameter = 15 nm
4. Length varies

11

Wall of microtubule cylinders consists of:

13 protofilaments arranged side-by-side, forming a hollow center

12

Protofilament

Forms microtubule cylinder

Heterodimer of tubulin

13

2 types of tubulin

Alpha-tubulin

Beta-tubulin

14

beta-tubulin

2 functions:

Forms:

1. Tubulin synthesis
2. Non-covalent binding

Forms alpha-beta heterodimers

15

How many tubulin isoforms in brain?

5 alpha, 5 beta

16

Microtubule orientation

Radiate toward periphery → forms centrosome

17

How are microtubules regulated?

Microtubule associated proteins (MAPs)

18

Where do MAPs bind?

What is their function?

Regular intervals along wall of microtuble:
1. Allows interaction with other filaments
2. Regulate growth of microtubule

19

2 types of MAPs in brain

1. Motor MAPs
2. Non-motor MAPs

20

Motor MAPs

Use ATP to drive transport of vesicles and organelles

21

Function of non-motor MAPs

1. Control microtubule organism in cytoplasm
2. Nervous system

22

Neurites

Non-motor MAP in brain reinforced by microtubules

23

Neurites can differentiate into?

1. Axons
2. Dendrites

24

Microfilament composes?

1. Contractile fibers of muscle cells (actin)
2. Microvilli
3. Cell cortex

25

Cell cortex function

Mechanical support of plasma membrane → responsible for cell-surface movement

26

Cell cortex is a dense network of microfilaments. Tell me about it.

Microfilaments are attached to the inner face of plasma membrane → causes cell surface to be structurally rigid (important in cell shape)

27

Actin

1. Extremely abundant → in virtually all cells
2. Building block of microfilaments

28

G-Actin

Individual actin

29

F-Actin (filamentous)

Polymerization of G-Actin

30

Actin nomenclature

1. G-Actin
2. F-Actin

31

2 major groups of actin

1. Muscle-specific
2. Non-muscle

32

Muscle-specific actin

apha-actin

33

Non-muscle actin

beta-actin and gamma-actin

34

Cell surface extensions

Extend from edge of migrating cell → aids in movement of cell

35

Actin-binding protein functions

1. Stabilize filaments
2. Generate force (myosin)

36

Intermediate filament roles

1. Structure
2. Tension-bearing

37

Intermediate filament properties

1. Most stable
2. Least soluble
2. Scaffold (supports entire cytoskeleton)

38

Intermediate filament structure differs based on?

Amino acid composition between tissues

39

6 classes of intermediate filaments

I and II: epithelial cells
III: muscle, glial, CT
IV: nerve cels
V: all cells
VI: embryonic nervous system

40

How is mechanical stress important in normal physiological processes?

1. Cell growth
2. Function
3. Differentiation
4. Apoptosis

41

2 diseases in which mechanical stress is especially relevant

Heart and lung diseases

42

Adaptation from mechanical stress occurs via changes in:

1. Structure
2. Metabolism
3. Gene expression

43

Tensegrity structure

Uses tension and compression to provide support

Tensegrity = tensional integrity

44

What generates tension?

Microfilaments

45

What bears compression?

Microtubules

46

What provides elasticity?

Intermediate filaments

47

How does cytoskeleton adapt to stress?

Transmits stress to rest of structure → aligns tension bearing forces with direction of stress

48

Signaling response to stress

ECM recognizes stress → transmits signal into cell so it can adapt as needed

49

3 responses to stress

1. Outside-in signaling
2. Regulation of nuclear access
3. Adaptation of cytoskeleton and ECM

50

How is nuclear access regulated as a response to stress?

Alters pore size leading to nucelus

51

How does membrane respond to stress?

Mechanically gated ion channels

52

Centrosome

Microtubule organizing center

53

Neurites → Axons regulated by?

Tau

54

Neurites → Dendrites regulated by?

MAP2

55

Microfilaments found in what cells?

Almost all eukaryotic cells

56

Cell cortex is made of?

Dense network of microfilaments

57

Proper function of non-motor MAPs in the nervous system is dependent on?

Neuron and non-neuron interactions