Cytoskeleton and Response to Mechanical stress

Question 1

What are the cytoskeleton components?

Answer 1

Microtubules, microfilaments, intermediate filaments

Question 2

What is the most important role of the cytoskeleton?

Answer 2

Internal organization (cell shape)

Question 3

What are the largest structural elements?

Answer 3

Microtubules

Question 4

What are the smallest structural elements?

Answer 4

Microfilaments

Question 5

What structural element is between these?

Answer 5

Intermediate fibers

Question 6

What is the function of microtubules?

Answer 6

Cellular movement (Cilia, Flagella)

Maintenance of nerves & axons

Spatial orientation in cytosol

Question 7

Do microtubules have a solid center?

Answer 7

No. Formed by protofilaments with a hollow center

Question 8

What are protofilaments?

Answer 8

Tubulin (alpha-beta heterodimer)

Question 9

What tubulin isoform does the brain use?

Answer 9

5-alpha, 5-beta

Question 10

Where are microtubules found in relation to the cell?

Answer 10

Periphery

Question 11

What are MAPs?

Answer 11

Microtubule Associated Proteins

Bind along wall of microtubule and regulates growth and interaction with other filaments

Question 12

Where are non-motor MAPs found?

Answer 12

Brain

Control microtubule organization

Question 13

What are motor MAPs?

Answer 13

Drive tansport of vesicles/organelles

Question 14

What MAP factors regulate Axons and Dendrites?

Answer 14

Axons - Tau (Alzheimers)

Dendrites - MAP2

Question 15

What is the main function of microfilaments

Answer 15

Contractile fibers of muscle (actin)

Microvilli

Question 16

What is G Actin? F-Actin?

Answer 16

G-Actin: Individual Actin

F-Actin: Polymerization of G-Actin

Question 17

Which actin is muscle specific?

Answer 17

alpha-actin

Question 18

What are microspikes?

Answer 18

Cell surface extensions that aid in cell movement

Question 19

What are actin binding proteins? What do they do?

Answer 19

Myosin

Stabilizes filaments & generates force

Question 20

What is the function of intermediate filaments?

Answer 20

Most stable
Tension-bearing
Least soluble
Acts as scaffold to support cytoskeleton

Question 21

How many classes of intermediate filaments are there?

Answer 21

6

Question 22

What is Class I & II Intermediate filaments?

Answer 22

Epithelial cells

Question 23

What is class 3 intermediate?

Answer 23

Muscle, glial, connective tissue

Question 24

What is class 4 intermediate?

Answer 24

Nerve cells

Question 25

What is class 5 intermediate?

Answer 25

All cells

Question 26

What is class 6 intermediate?

Answer 26

Embryonic nervous system

Question 27

Why do changes/adaptation occur in cytoskeleton?

Answer 27

Mechanical stress like structure, metabolism, gene expression

Question 28

What is tensegrity?

Answer 28

Use tension (pull) and compression (push) to provide support

Question 29

What structural elements provide the tension?

Answer 29

Microfilaments (cables)

Question 30

What structural elements provide elasticity?

Answer 30

Intermediate filaments (cables)

Question 31

What structural elements provide Compression?

Answer 31

Microtubules (Pillars)

Question 32

How does cytoskeleton transmit stress?

Answer 32

From 1 point to the rest of the structure so that tension bearing forces align with the stress

Question 33

What is an example of cytoskeleton changes due to mechanical stress?

Answer 33

RBCs passing through capillary and becoming temporarily distorted

Mechanical Gated Ion channel is opened by mechanical pressure

Question 34

How are cells signalled to adapt?

Answer 34

ECM recognizes stress and signals for change

Regulation of nuclear access by altering pore size

Cytoskeleton & ECM can confirmationally change so they go to signalled site