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EXAM 1- Anatomical Sciences > Cytoskeleton > Flashcards

Cytoskeleton Flashcards

1
Q

Cytoskeleton definition

A

System of protein polymers that provide for the architecture, shape, motility of cells and for the directed movement of organelles and molecules within the cell

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2
Q

Components of cytoskeleton

A

Microtubules, microfilaments (actin filaments), intermediate filaments

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3
Q

Microtubules are polymers of ______, which is a ____ase

A

Tubulin dimers, GTP

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4
Q

MAPs do what ?

A

Stabilize and space Microtubule polymers and regulate interactions between cytoskeletal elements

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5
Q

MT - dynamic or no?

A

Highly dynamic, undergo rapid bouts of assembly and disassembly

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6
Q

MTs are polarized, Which end of the MT is dynamic?

A

PLUS END

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7
Q

Functions of MT

A

Make up mitotic spindle
Provide railways for organelle transport in most interphase cells
Key determinant of cell shape
Important in neurons for cell shape and axonal transport
Provide the backbone for cilia and flagella

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8
Q

Which cytoskeleton aspect is important for neurons?

A

MT, cell shape and axonal transport

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9
Q

Which cytoskeletal element is the backbone for cilia and flagella?

A

MT

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10
Q

What is a protofilament?

A

Stacks of tubulin dimers

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11
Q

Around how many protofilaments make up a MT

A

13

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12
Q

The catastrophe phase of MT dynamics refers to ?

A

Depolymerization

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13
Q

The catastrophe phase of MT dynamics refers to ?

A

Depolymerization

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14
Q

The rescue phase of MT dynamics refers to ?

A

Polymerization phase

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15
Q

Tubulin is a ____ase

A

GTP

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16
Q

The GTP cap exists on MT during which phase?

A

Polymerization phase

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17
Q

Tubulin dimers must be loaded with _____ for polymerization to happen

A

GTP

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18
Q

A regular MT polymer not going thru polymerization is ____ loaded

A

GDP

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19
Q

What is dynein? Which end of polymer is it directed to?

A

Microtubule associated motor protein, NEG end

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20
Q

What is Kinesin? Which end of polymer is it directed to?

A

Microtubule associated motor protein, POS end

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21
Q

The head domain of MAMPs is bound to ____

A

Microtubules, they STEP

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22
Q

Function of light / light&intermediate chains

A

Decided the cargo that motor proteins will carry, regulate the motor proteins and speed it travels

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23
Q

Functions of MAPs (non motor) and examples

A

Organize MTs, regulate MT stability, regulate MT dynamics
Tau, MAP1A etc

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24
Q

Nucleation of MTs occurs at the ______

A

Centrosome

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25
Q

The centrosome is located

A

Near the nucleus

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26
Q

Nucleation =

A

Genesis of a cytoskeletal polymer

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27
Q

Centrosome structure

A

2 centrioles
Gamma tubulin on - end of MT

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28
Q

Where are cilia located

A

Lung epithelium, trachea, fallopian tubes

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29
Q

MTs are important in sperm because

A

They allow sperm to move (tail)

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30
Q

Function of cilia

A

Move mucus / other substances

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31
Q

What is the basal body

A

Microtubule organizing center for cilia and flagella

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32
Q

Where are cilia Nucleated

A

At the basal body, under the membrane

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33
Q

What is the axoneme

A

9+2 MT structure of cilia and flagella

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34
Q

What connects the outer doublets to the inner doublet in cilia/flagella

A

Dynein

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35
Q

What is the purpose of dynein in cilia and flagella

A

Connects doublets to center, allows Microtubules to move in relation to each other (AKA bending)

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36
Q

Immotile cilia syndrome

A

Body wide defect in axonemal structure that result in obstructive lung disease and sterilization in males
(Can’t move mucus or repel sperm)

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37
Q

Kartagener’s syndrome

A

Combination of situs in versus (reversal of normal body asymmetry) and immotile cilia syndrome
Cilia not functional during early development = cells move to wrong spots and develop organs there

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38
Q

How are MTs related to cancer?

A

Cell division is reliant on MTs, if you mess with cell replication, cancer can result

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39
Q

How do neurotopic viruses exploit MTs?
Example?

A

Vectors bind to motor proteins and get transported all around cell; leads to gene expression of the virus in those cells
Herpes virus

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40
Q

How is lissencephaly related to MTs?

A

Mutations in LIS1 and double cortin
(Smooth brain)

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41
Q

How are MTs related to Charcot-Marie-tooth disease type 2A?

A

Mutation in specific kinesin

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42
Q

How are neurodegenerative diseases related to MTs?

A

Abnormalities/ mutations in tau, dynein, kinesis, spastin

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43
Q

What is the smallest of the cytoskeletal elements?

A

Microfilaments (actin filaments)

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44
Q

Structure of microfilaments

A

Helical (two chains wrapped around each other)
Non hollow

45
Q

Microfilaments are polymers of ___

A

Actin

46
Q

Are microfilaments dynamic or no

A

Highly dynamic if not stabilized

47
Q

Actin is a ____ase

A

ATP

48
Q

Where are microfilaments nucleated

A

Anywhere in the cell!

49
Q

What motor proteins use microfilaments as a substrate

A

Myosin family of motor proteins

50
Q

Polarized structure of microfilaments has what ends

A

Barbed (+) and pointed (-)

51
Q

What end of microfilaments is favored for assembly

A

Barbed end

52
Q

Most myosins moved towards the ___ end on microfilaments

A

Barbed

53
Q

Functions of microfilaments

A

Concentrated in cell cortex for various functions
Cleavage furrow for pinching off cells in final stages of mitosis
Cell motility
Short range organelle transport (via myosin mp)
Contractility (muscle and non muscle)

54
Q

Actin has ___ isoforms, what are they ?

A

3, alpha, gamma, beta

55
Q

Which actin isoforms are found in most cells? Which is specific and for what?

A

Beta and gamma, alpha is specialized for muscle

56
Q

What accessory protein is often bound to the structure of actin filaments

A

Tropomyosin (rope around)

57
Q

Actin must be ____ loaded for Nucleation and polymerization

A

ATP

58
Q

What does the NPF do in actin filaments Nucleation

A

Creates the ARP2/3 complex by grabbing actin molecules
Complex first binds to the side of an existing actin filament, then Nucleates a new filament off of other side
ALLOWS FOR BRANCHING AND NETWORKS

59
Q

What is a spire

A

Actin filaments with accessory protein bound (like a string to help Nucleation

60
Q

What are forming

A

Actin filaments with accessory protein bound (like a ring around filament) to help Nucleation

61
Q

Actual actin filaments exist with actin bound to

A

ADP

62
Q

Monomer sequestering meaning (AF)

A

Monomer bound to depolymerizing proteins, can’t be used until protein comes off

63
Q

Capping meaning (AF)

A

Cap placed on barbed end, stops polymerization to make short capped filaments

64
Q

Crosslinking meaning (AF)

A

Happens with short capped filaments or long filaments, creates bundles or networks that have structural functions and other functions within cytoplasm

65
Q

Annealing meaning (AF)

A

Joining short uncapped filaments into long filament

66
Q

What is made of F actin

A

Stress fibers, leading edge mesh works

67
Q

What are stress fibers made of and what is their purpose

A

Myosin, a-actin in, formins (help Nucleation)
Basically the muscle for the cells
Contractibility

68
Q

What are leading edge mesh works made of and what is their purpose

A

Arp2/3 (branching) , profilin, cofilin, etc
Can change shape of cell

69
Q

What is a sarcomere made up of

A

Actin filaments that overlap with their pointed ends on the outside and barbed ends on the inside

70
Q

What is the purpose of F-actin associated force

A

Generating mechanoenzymes with roles in contractility and intracellular transport
Allows sarcomeres to contract

71
Q

Myosin 1 and myosin 5 have what light chains? What do they bind to ?

A

Calmodulin -binds to Ca2+ to control activity

72
Q

Myosin 2 has ___ types of light chains ? What are they

A

Regulatory and essential

73
Q

Regulatory light chains on myosin 2 are regulated by ___

A

Kinases

74
Q

Essential light chains on myosin 2 regulate by

A

Binding to myosin - function like an off/on switch

75
Q

Functions /structure of actin during cytokinesis

A

Ring of actin and myosin binds; contracts and pinches off cells
Myosin 2 & F actin in ring
Myosin 1 at poles

76
Q

What forms of myosin and actin are present in the cleavage furrow

A

Myosin 2 and F actin

77
Q

Microvilli are ____ based epithelial projections
They are located where in the body?

A

Actin
Small intestine ( 4 absorption during digestions)

78
Q

What structure functions in the ear cells to detect sound waves ? What are they made of

A

Stereocilia, actin filaments

79
Q

The _____ end of the actin filaments are located at the tip of the microvilli

A

Barbed

80
Q

The ______ domain of lateral arms binds to membrane in microvilli
What is this made of ?

A

Hydrophobic
Myosin 1 (monomeric) & calmodulin

81
Q

What is the purpose of the lateral arms in microvilli

A

Attach to actin filaments that make up structure, stabilizes filaments by binding to the membrane

82
Q

What stabilizes the array of microfilaments in the microvilli

A

Villin and fimbrin

83
Q

The physical link between the cytoskeleton and the extracellular environment provides ___

A

Mechanical continuity

84
Q

Erythrocyte (RBC) cytoskeleton is made up of

A

Spectrum tetramers (strings) and f-actin (scaffold) to form the spectrin web
The actin serves as nodes ; makes shape

85
Q

Hereditary spherocytosis

A

Deforms red blood cells to fragile spherocytes because of weakened binding affinity of spectrin to band 4.1

86
Q

Hereditary elliptocytosis

A

Deforms red cells to fragile elliptocytes because of incomplete formation of spectrin

87
Q

Breast cancer related to actin

A

In some forms of actin associated protein Tensin (links integrity receptors to the actin cytoskeleton, is disrupted promoting metastatic migration of cancerous cells

88
Q

Familial hypertrophic cardiomyopathy

A

Mutations in a specific cardiac actin
Only myocardium impacted

89
Q

Mutations in skeletal muscle actin are associated with ____ characterized by _______ abnormalities of the muscle and variable degrees of muscle _____

A

Congenital myopathies, structural, weakness

90
Q

Mutations in VI cause

A

Deafness; prevent proper formation of stereocilia

91
Q

Mutations in myosin VII associated with

A

Deafness, neurological disorder, and blindness (Usher syndrome type 1)

92
Q

How do bacterial pathogens use cytoskeletal elements

A

Bacterium moves by developing actin-Nucleation-like proteins to push around bacterium

93
Q

Phalloidin causes cells to ____ by

A

Die, binding and stabilizing actin filaments
Cells will die because actin dynamics=0

94
Q

Intermediate filaments are dynamic or no

A

Not dynamic, don’t have a polarized side

95
Q

Functions of intermediate filaments

A

Space filling elements (increases cell volume)
Give cells tensile strength (structural stability)
Specialized functions depending on cell type
Important at cell junctions

96
Q

Intermediate filaments are much ___ conserved across cell types than Microtubules or microfilaments

A

Less

97
Q

What cytoskeletal elements can be used as cell specific markers

A

Intermediate filaments

98
Q

Intermediate filament formation

A

Helical string with (NH2 end and COOH end)
Coiled dimer
Two coiled dimers together (protofilament) (lego brick)
Stacks like legos

99
Q

Keratins are which type of cytoskeletal element
Where are they found

A

Intermediate filaments
Epithelial cells and epidermal derivatives

100
Q

Nuclear lamins are what type of cytoskeletal elements
Where are they found

A

Intermediate filaments
In the nuclei of every cell

101
Q

Epidermolysis bullnose simplex

A

Mutation in keratin genes expressed in basal cell layer of epidermis, result in a skin that is very sensitive to mechanical injury
*dangerous because it opens skin to infection

102
Q

Progeria

A

Fast aging disease associated with mutation in nuclear lamin protein

103
Q

Intermediate filaments differ in different cells means that disease …..

A

Specific diseases are associated with specific problems

104
Q

Keratins are mutated in more than ____ diseases

A

20

105
Q

Desmin is mutated in

A

Cardiomyopathies

106
Q

Neurofilament proteins are mutated in

A

(Small subunit mutated in the IF/2E forms of Charcot-Marie tooth disease

107
Q

Peripherin is induced after

A

Peripheral nerve industry

108
Q

Glial fibrillation acidic proteins are mutated in

A

Alexander disease (a leukodystrophy, which results in abnormal myelin)

EXAM 1- Anatomical Sciences (6 decks)

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