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Cell Biology And Signaling > Cytoskeleton > Flashcards

Cytoskeleton Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Definition of cytoskeleton

A

Network of protein filaments, tubules in cytoplasm, gives shape and coherence

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2
Q

Function of cytoskeleton

A 
Connection with ECM
Maintaining cell shape
Intercellular transport
Cytokinesis
Chromosome separation
Cell movement
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3
Q

Composition of cytoskeleton

A

Actin microfilaments
Intermediate filaments
Microtubules

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4
Q

Diameter of actin polymers

A

7-9nm

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5
Q

Diameter of tissue specific proteins in intermediate filaments

A

10nm

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6
Q

Diameter of tubulin polyerms

A

25nm

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7
Q

Formation of actin microfilaments

A

G actin, globular protein has ATP binding domain on left
G actin polymerizes to form F actin (microfilament), involves ATP hydrolysis via non covalent interactions
Forms 2 tightly wound chains

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8
Q

Is actin a dynamic structure?

A

Yes, length depends on the rate of loss and gain of G actin

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9
Q

Function of actin

A

Muscle contraction
Mechanical support (microvilli)
Maintaining cell shape
Cell movement

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10
Q

Actin binding proteins

A

G actin binding proteins
Cross linking proteins
Severing

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11
Q

Example of G actin binding proteins

A

Thymosin B4, inhibits polymerisation

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12
Q

Examples of cross linking proteins in actin

A

Villin, parallel bundles in microvilli

Filamin, joining at angles to create a mesh

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13
Q

Examples of severing proteins in actin

A

Gelsolin, cuts and binds to +ve end, depolymerizes other side

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14
Q

Contraction in non muscle cells

A

Interaction between myosin and actin microfilaments + ATP hydrolysis = movement
Movement within cells
Movement of cells

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15
Q

How is actin involved in the movement within cells

A

Cytokinesis, actin ring forms in cell center, anchors to plasma membrane, myosin contraction constricts cell

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16
Q

How is actin involved in the movement of cells

A

Lamellipodia mediated cell movement across ECM

17
Q

Lamellipodia formation

A

Extensions of cells have actin network
Generated by rapid growth of actin filaments at cell membrane
Tip of lamellipodia interacts with ECM via integrins
Contraction involving myosin allows cell movement

18
Q

What are intermediate filaments

A

Polymers of individual IF proteins

19
Q

Types of IF proteins in different cell types

A

Epithelia, keratin
Axons, neurofilamin
Universal lamins ABC

20
Q

Function of keratin intermediate filaments in epithelia

A

Physical support, external structures

21
Q

Function of neurofilamin intermediate filaments in axons

A

Structural arrangement of axons

22
Q

Function of universal lamins ABC intermediate filaments

A

Support nuclear structure

23
Q

Properties of intermediate filaments

A

Usually stable, not dynamic

Except lamins, nuclear membrane reforms during mitosis

24
Q

Formation of IF polymers

A

Monomer
Helical dimer
Dimer + dimer = tetramer
Staggered formation of tetramers, end to end

25
Q

Structure of microtubules

A

Tubulin monomers, heterodimers of ab tubulin
Protofilament has -ve and + end
Monomers can be added rapidly and removed from +ve, -ve end
13 parallel protofilaments in hollow tube

26
Q

What is the microtubule organizing center (MTOC)

A

1 end of microtubule attached to MTOC
1 MTOC associated with nucleus
Microtubules grow out from MTOC until destination reached, stabilised

27
Q

Assembly and disassembly of microtubules

A

Formation:
FTP bound monomers assemble from +ve end

Disassembly:
GTP => GDP + Pi
GDP bound monomers dissociate rapidly

28
Q

Function of microtubules

A 
Dynamic scaffold
Movement of cargo to specific locations in cell
Central internal support of cilia
Stabilize cell structure (platelets)
Organise structure of organelles (ER)
29
Q

Why are microtubules dynamic

A

Spindle for chromatid separation during mitosis

30
Q

Spindle formation in mitosis and meiosis

A

Made up of microtubules
Formation initiated from centrosome (type of MTOC)
Centrosomes form at 2 cell poles
Kinetochore microtubules attach to chromatid
Aster microtubules attach centrosome to cell membrane

31
Q

Movement of cargo within cell

A

ATP hydrolyses to move cargo along MT
Kinesin moves towards +ve => cell periphery
Dynein moves towards -ve => nucelus

32
Q

Cilia and microtubules

A

Supported by MT
MTOC called basal body, close to membrane
MT facilitates movement of components up and down cilia
All cells have single primary cilia, disassembled during mitosis

33
Q

Specialized types of cilia

A

Stereocilia, sound detection

Motile, respiratory, waft

34
Q

cell-cell junctions, connected to CS

A

Desmosomes

Gap junctions

35
Q

ECM attachment connected to CS

A

Hemidesmosomes

Adherens junctions

Cell Biology And Signaling (11 decks)

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