Biom2021 - The Cytoskeleton

Front 1

List the 3 key functions of the Cytoskeleton.

Back 1

Structure and Support.

Intracellular Transport.

Contractility and Motility.

Front 2

Name the 3 types of cytoskeletal fibres.

Back 2

Intermediate Filaments.

Microtubules.

Microfilaments.

Front 3

Intermediate filaments are commonly made of what protein?

Back 3

Keratin

Front 4

Microtubules are mainly made of what protein?

Back 4

Alpha & Beta Tubulin

Front 5

Microfilaments are mainly made of what protein?

Back 5

Actin

Front 6

Intermediate filaments are composed of mainly Keratin. True or False?

Back 6

True

Front 7

Intermediate filaments are composed of mainly Actin. True or False?

Back 7

False

Front 8

Microtubules are composed of mainly Keratin. True or False?

Back 8

False

Front 9

Microtubules are composed of mainly Alpha and Beta Tubulin. True or False?

Back 9

True

Front 10

Microfilaments are composed of mainly Alpha and Beta Tubulin. True or False?

Back 10

False

Front 11

Microtubules are composed of mainly Actin. True or False?

Back 11

True

Front 12

Fill in the Blanks: The Cytoskeleton is a network of _______ _________ extending throughout all eukaryotic cells.

Back 12

Protein Filaments

Front 13

Intermediate filaments have an average diameter of 10nanometers, which is between that of 7 nm actin (microfilaments), and that of 25 nm microtubules. True or False?

Back 13

True

Front 14

Most types of intermediate filaments are cytoplasmic, but one type, the lamins, are nuclear. True or False?

Back 14

True

Front 15

Fill in the blank: The intermediate filaments are composed of ______________ wrapped in ropelike formation.

Back 15

Protofilaments

Front 16

Because the tetramers are antiparallel, Intermediate filaments are polar. True or False?

Back 16

False

Front 17

Because the tetramers are antiparallel, Intermediate filaments are non-polar. True or False?

Back 17

True

Front 18

There are different types of Intermediate Filaments. Type I and II both involve Keratin. What other 5 proteins were mentioned for different types?

Back 18

Lamins.

Desmin.

Peripherin.

GFAP.

Neurofilaments.

Front 19

What type of Intermediate filament do GFAP (Glial Fibrillary Acidic Protein), Desmin and Peripherin fall under?

Back 19

Type III

Front 20

What type of Intermediate filament do Neurofilaments fall under?

Back 20

Type IV

Front 21

What type of Intermediate filament do Nuclear Lamins fall under?

Back 21

Type V

Front 22

Keratins are either acidic or basic. Acidic and basic keratins bind each other to form acidic-basic heterodimers and these heterodimers then associate to make a keratin filament. True or False?

Back 22

True

Front 23

There are Hair Keratins and Epithelial Keratins. True or False?

Back 23

True

Front 24

Desmin Intermediate Filaments are structural components of the ___________ in muscle cells

Back 24

Sarcomeres

Front 25

GFAP (glial fibrillary acidic protein) Intermediate Filaments are found in ___________ and other glia.

Back 25

Astrocytes

Front 26

Peripherin Intermediate Filaments are found in ___________ neurons.

Back 26

Peripheral

Front 27

Neurofilaments are a type IV intermediate filament which are found in high concentrations along the ______ of vertebrate neurons.

Back 27

Axons

Front 28

Lamins are fibrous proteins that have a structural function in the ____ ________.

Back 28

Cell Nucleus

Front 29

There are A and B type lamins. B-type lamins are present in every cell. A-type lamins are only expressed following gastrulation. True or False?

Back 29

True

Front 30

There are A and B type lamins. A-type lamins are present in every cell. B-type lamins are only expressed following gastrulation. True or False?

Back 30

False

Front 31

Intermediate Filaments (IFs) associate with the nucleus, the plasma membrane and with other elements of the cytoskeleton, thus integrating into an internal cytoskeleton. True or False?

Back 31

True

Front 32

In epithelial cells _______ filaments are anchored to the plasma membrane in specialised regions of cell contact, called ________________.

Back 32

Keratin.

Desmosomes.

Front 33

Desmosomes are regions of cell-cell adhesion mediated by what protein?

Back 33

Cadherin

Front 34

On the cytoplasmic side, desmosomes are associated with a dense plaque of intracellular protein to which keratin is attached. True or False?

Back 34

True

Front 35

Keratin filaments anchored to both sides of the desmosome serve as a mechanical link between adjacent cells, providing what to the entire tissue?

Back 35

Mechanical Stability

Front 36

Epidermolysis (EB) is a rare genetic disease charactarised by fragile skin and recurrent blister formation. It can involve a mis-sense mutation on which two genes?

Back 36

KRT5 or KRT14

Front 37

The mutation of KRT5 or KRT14 leads to which disease?

Back 37

Epidermolysis

Front 38

Epidermolysis (EP) results in mutated _______ filaments unable to form the cellular support infrastructures necessary for cell stability and durability.

Back 38

Keratin

Front 39

Microfilaments (Actin Filaments) are the major cytoskeletal protein of most cells. It is also a polymer of actin monomers organised into higher order structures. True or False?

Back 39

True

Front 40

There are 3 major features to Microfilaments: Polymerisation & De-polymerisation,

Crosslinking into bundles & networks,

Association with membrane.

True or False?

Back 40

True

Front 41

Micro/Actinfilaments are ________ than microtubules.

Back 41

Smaller

Front 42

An actin monomer is known as what?

Back 42

G Actin

Front 43

G Actin is an actin monomer which polymerises to form what?

Back 43

F Actin

Front 44

Is F-actin a polarised or non-poloarised structure?

Back 44

Polarised

Front 45

Actin filaments are dynamic structures which allows ________________ to be reversible.

Back 45

Polymerization

Front 46

Polymerization of actin filaments occur preferentially at one end causing a "treadmilling" effect. True or False?

Back 46

True

Front 47

Actin filaments have 2 distinctive ends. What are they called?

Back 47

Pointed.

Barbed.

Front 48

Actin filaments depolarize at which end?

Back 48

Pointed

Front 49

Actin filaments polarize at which end?

Back 49

Barbed

Front 50

G-actin binds to ATP which _____________ to ADP as it becomes F-actin.

Back 50

Hydrolyses

Front 51

Which end of the F-actin are G-actin bound to ATP?

Back 51

Barbed

Front 52

Which end of F-actin are G-actin bound to ADP?

Back 52

Pointed

Front 53

ATP-F-actin deploymerizes much more readily than ADP-F-actin. True or False?

Back 53

False

Front 54

ADP-F-actin deploymerizes much more readily than ATP-F-actin. True or False?

Back 54

True

Front 55

Actin treadmilling is important for cell migration, shape/structure, proliferation, growth and movement. True or False?

Back 55

True

Front 56

Growth Factor receptor stimulation leads to activation of Rho family of small g-proteins, ___ __ and ___ which in turn activate downstream signalling and activation of the ______ protein complex.

Back 56

Cdc 42.

Rac.

Arp2/3.

Front 57

Arp2/3 is an _______ binding protein.

Back 57

Actin

Front 58

The _______ protein complex controls nucleation of G-actin and the formation of F-actin.

Back 58

Arp2/3

Front 59

The Arp2/3 protein complex controls ___________ of G-actin and the ___________ of F-actin.

Back 59

Nucleation.

Formation.

Front 60

The formation of a filament, or initiation of side branches is inhibited by the Arp2/3 protein complex. True or False?

Back 60

False

Front 61

The formation of a filament, or initiation of side branches is accelerated by the Arp2/3 protein complex. True or False?

Back 61

True

Front 62

Forward motion at the leading edges of a mobile cell is created by ____ dynamics

Back 62

Actin

Front 63

Name an example of where other actin binding proteins stabilise actin filaments.

Back 63

Skeletal Muscle

Front 64

In skeletal muscle, the CapZ binds to the Barbed end, whilst Tropomodulin caps the Pointed end. True or False?

Back 64

True

Front 65

Microtubules have which 3 major features; What are they?

Back 65

Assembly & Disassembly.

Association with microtubule motors.

Role in intracellular transport.

Front 66

Microtubules are polymers of a single globular protein called what?

Back 66

Tubulin

Front 67

Tubulin is a dimer consisting of two polypeptides which are known as what?

Back 67

Alpha & Beta Tubulin

Front 68

How many tubulin polymers (aka protofilaments) form around a hollow core to create a microfilament?

Back 68

13

Front 69

Are Microtubules polarised or non-polarised?

Back 69

Polarised

Front 70

Microtubules have a slowly forming + end and a quickly forming - end. True or False?

Back 70

False

Front 71

Microtubules have a rapidly forming + end and a slowly forming - end. True or False?

Back 71

True

Front 72

Each tubulin subunit initially binds to what?

Back 72

GTP

Front 73

Alpha Tubulin binds GTP but _______ _________ it.

Back 73

Doesn't Hydrolyse

Front 74

Beta Tubulin binds GTP but __________ _________ it to GDP on polymerasization.

Back 74

Rapidly Hydrolyses

Front 75

Growth at the + end of Microtubules continues as long as there is a high concentration of GTP/GTP-Tubulin. True or False?

Back 75

True

Front 76

If GTP/GTP-Tubulin concentration falls, hydrolysis rate becomes _________ than the cap rate, causing depolarization from _____ ________.

Back 76

Faster.

Both Ends.

Front 77

Microtubule dynamics are complex, underlying crucial cell processes. These include:

> Cell growth

> Polarized cell migration

> Chromosomal segregation

>Cell Movement

And what other process?

Back 77

Intracellular Vesicle Transport

Front 78

In cells, Microtubules are not randomly distributed but radiate from the ______________.

Back 78

Centrosome

Front 79

What does MTOC stand for?

Back 79

Microtubule Organising Centre

Front 80

The Microtubule Organising Centre (MTOC) orients most microtubules and determines what?

Back 80

Cell Polarity

Front 81

In a neuron, stable microtubules exist in the _____.

Back 81

Axon

Front 82

Microtubules are the highways in which the movement of intracellular vesicles & organelles occurs. True or False?

Back 82

True

Front 83

What accomplishes the movement of intracellular vesicles and organelles across Microtubules?

Back 83

Microtubule Motor Proteins

Front 84

Name the 2 families of Microtubule Motor Proteins.

Back 84

Kinesin, Dyneins

Front 85

Dyneins move towards the +ve end whilst Kinesins move towards the -ve end of Microtubules. True or false?

Back 85

False

Front 86

Dyneins move towards the -ve end whilst Kinesins move towards the +ve end of Microtubules. True or false?

Back 86

True

Front 87

In a neurons _____, the microtubules are stable.

Back 87

Axon

Front 88

Microtubules in the Axon of a neuron are oriented in such a way that the +ve end tends towards the cell body and the -ve end tends towards the dentrite. True or False?

Back 88

False

Front 89

Microtubules in the Axon of a neuron are oriented in such a way that the -ve end tends towards the cell body and the +ve end tends towards the dentrite. True or False?

Back 89

True

Front 90

Is MAP-1C a dynein or a kinesin?

Back 90

Dynein

Front 91

Name the example of a kinesin given in the lecture.

Back 91

Kinesin-1

Front 92

Kinesin-1 conducts ___________ axonal transport, to the dentrite.

Back 92

Anterograde

Front 93

MAP-1C Dynein conducts ___________ axonal transport, to the neurons cell body.

Back 93

Retrograde