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Flashcards in MCB 3rd Unit 1 Deck (147)
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1
Q

Filament that supports cell shape and structure as well as forming a band to separate dividing cells

A

Actin

2
Q

Free actin monomers are referred to as:

A

Globular actin or G-actin

3
Q

F actin is:

A

Actin monomers creating a double helix = microfilaments or thin filaments (myofibrils)

4
Q

Thick filaments are made from:

A

Myosin motor proteins

5
Q

Thin filaments are associated with:

A

Myofibrils (muscle)

6
Q

Which end of the actin filament is slow growing?

A
  • end
7
Q

Which part of the actin filament is fast growing?

A

+ end (bind monomers with affinity due to ATP)

8
Q

The change from ATP to ADP is what type of chemical process?

A

Hydrolysis

9
Q

Adding ATP bound G-actin monomers to the + end of the filament whilst ADP bound monomers are removed at the - end, resulting in a filament that maintains the same length is a process called:

A

Treadmilling

10
Q

Shrinkage and growth (catastrophe and rescue) termed “dynamic instability” was a characteristic of:

A

Microtubules

11
Q

True or false, affinity of actin monomers follows this progression:
Filament>nucleus>each other

A

True

12
Q

What protein exchanges ADP for ATP, readying the monomer for attachment?

A

Profilin

13
Q

What protein stimulates nucleation of G-actin into dimers/trimers

A

Arp 2/3

14
Q

What protein initiates polymerization if actin?

A

Arp 2/3

15
Q

The ARP complex nucleates filaments more effectively when bound where?
What does this create?

A

To the side of preexisting actin filaments, a branched/webbed actin network

16
Q

What protein nucleates the growth of straight, unbranched actin filaments which become crosslinked by other proteins forming parallel bundles?

A

Formins

17
Q

Which protein binds G-actin and prevents F-actin assembly?

A

Thymosin

18
Q

What protein binds G-actin and promotes filament assembly at the + end? (Actin ADP->ATP)

A

Profilin

19
Q

What protein caps the + end of the actin filament to prevent further growth?

A

Gelsolin

20
Q

What protein severes and depolymerizes ADP actin filaments?

A

Cofilin

21
Q

Which type pf myosin is involved with contractile activity (both muscle and non-muscle)

A

Myosin II

22
Q

Which type of myosin is involved in protrusion of actin-rich structures like microvilli?

A

Myosin I

23
Q

Which type of myosin is involved in vesicle and organelle transport?

A

Myosin V

24
Q

Name 3 actin cross-linking proteins which form parallel cables/bundles

A

Alpha-actinin, fimbrin, and villin

25
Q

Name 2 actin cross-linking proteins which form filament webs/gels

A

Spectrin and filamin

26
Q

Actin bundles and web-like organizations are initiated by ___ and stabilized by ____.

A

Nucleating proteins, cross-linking proteins

27
Q

Name four non-muscle functions of actin

A

Microvilli
Stress fibers
Cell surface protrusions (cell migration)
Cytokinesis

28
Q

Alpha-actinin is loosely packed and contractile, used for:

A

Stress fibers

29
Q

Fimbrin is tightly packed and non-contractile, used for:

A

microvilli

30
Q

How do actin stress fibers within the cell bind to ECM to allow movement?

A

Use integrin receptors at “focal adhesion” sites

31
Q

What proteins at the cell surface activate nucleating proteins (arp 2/3 complex and formins)?

A

Rho GTPases

32
Q

RhoGTPases located at the cell surface activate:

A

nucleating proteins

33
Q

Which RhoGTPase is responsible for formation of lamellipodia?

A

rac

34
Q

Which RhoGTPase is responsible for formation of filipodia?

A

cdc42

35
Q

Which RhoGTPase is responsible for formation of stress fibers?

A

rho

36
Q

A severe X-linked immunodeficiency syndrome involving a mutation in WASP protein resulting in an inability to activate Arp2/3 and thus failure of actin nucleation

A

Wiskott-Aldrich Syndrome

37
Q

Name 3 drugs t hat can bind to actin filaments

A

Cytochalasins, plahhoidin, latrunculin

38
Q

Thick filaments of myofibrils are made up of:

A

Hundreds of myosin II motor proteins

39
Q

Thin filaments of myofibrils are made up of:

A

Actin filament with tropomyosin and tryponin complex

40
Q

What protein links the actin cytoskeleton with the integral membrane glycoprotein complex that interacts with the ECM?

A

Dystrophin

41
Q

Dystrophin links the actin cytoskeleton to which protein specifically?

A

Laminin-2

42
Q

Muscle is repaired by which cell populations? Which does more?

A

Satellite cells and side population cells, satellite cells

43
Q

What is a bloodwork flag for muscular damage?

A

Increased serum creatine kinase

44
Q

What is the most severe type of muscular dystrophy and what is it’s inheritance pattern?

A

Duchenne MD, X-linked

45
Q

Which type of LGMD is AR?

A

LGMD 2

46
Q

Congenital muscular dystrophy involves a mutation in what protein?

A

Laminin

47
Q

What is an adhesive glycoprotein that anchors epithelial cells to the basal lamina via integrin receptors?

A

Laminin

48
Q

What type of collagen binds with laminin to form scaffold for basal lamina?

A

Collagen type IV, “sheet forming” collagen

49
Q

What two ECM proteins bind laminin and collagen IV, connecting the two networks?

A

Entactin and perlecan

50
Q

GAG’s carry what charge? How does this attract water?

A

Negative charge attracts cations which attract water

51
Q

In hyperglycemia, downregulation of ____ causes collagen glycosylation and cross-linking causing thickening of the GBM

A

HSPG

52
Q

Integrin receptors bind to the ____ sequence of fibronectin/laminin

A

RGD

53
Q

What type of fibronectin is made by the liver and circulates in the blood enhancing clotting?

A

Soluble plasma fibronectin

54
Q

What type of fibronectin is formed on the cell surface and deposited in the ECM?

A

Insoluble fibronectin fibrils

55
Q

Integrins bind laminin in the _____ and fibronectin in the ____.

A

Basal lamina, connective tissue

56
Q

In _____, integrins bind keratin intermediate filaments in the cell cia adaptor proteins (plectin) and to laminin in the basal lamina

A

Hemidesmosomes

57
Q

In _______ adhesions, integrins bind to actin stress fibers via adaptor proteins (vinculin and talin), and to fibronectin in the connective tissue

A

Focal adhesions

58
Q

______ cross links actin stress fibers

A

Alpha-actinin

59
Q

The purpose of focal adhesions is:

A

Motility

60
Q

Fillipodia are for ____, while lamellopodium are for _____.

A

Sensing, movement

61
Q

What GTPase rearranges actin to stretch into lamellopodium? Which mediates formation of stress fibers and new focal contacts?

A

RAC, RHO

62
Q

What GTPase regulates filopodia protrusion?

A

Cdc42

63
Q

What are the four types of cell-cell junctional complexes?

A

Tight
Adherins
Desmoses
Gap

64
Q

An adhesive protein that binds to sugars instead of other proteins is a:

A

Lectin

65
Q

A disease caused by absence of platelet integrin complex (aka glycoprotein Ilb-IIIa) and consequential failure of platelet aggregation

A

Glanzmann Thrombasthenia

66
Q

Articular and hyaline cartilage are formed from which type of collagen

A

Type II collagen forms articular and hyaline cartilage

67
Q

Constitutive activation of the RTK FGFR3 inhibits proliferation of what cell type, and thus causes what condition?

A

Chondrocytes. achondroplasia

68
Q

What type(s) of collagen form sheets?

A

Collagen types IV and X

69
Q

What type(s) of collagen form anchoring fibrils?

A

Collagen type VII

70
Q

What are the fibrillar collagens?

A

Collagen types I, II, III, and V

71
Q

What are the Fibril Associated (Networking) Collagens with Interrupted Triple helices (FACIT’s)?

A

Collagen type VI, IX, and XII

72
Q

MMP-1 degrades collagen type ___, while MMP-2 is a collagenase for type____.

A

I, IV

73
Q

Osteogenesis Imperfecta is associated with what type(s) of collagen?

A

Collagen type I

74
Q

Ehlers-Danlos Syndrome is associated with what type(s) of collagen?

A

Collagen types I, III, and V

75
Q

Alport Syndrome is associated with what type(s) of collagen?

A

Collagen type IV

76
Q

Goodpasture Syndrome is associated with auto-antibodies to what type(s) of collagen?

A

Collagen type IV

77
Q

Dystrophic Epidermolysis bullosa is associated with what type(s) of collagen?

A

Collagen Type VII

78
Q

Inherited Epidermolysis Bullosa Simplex is caused by a mutation in ____

A

Keratin 5 or 14

79
Q

What GAG forms the central core of proteoglycan aggregates?

A

Hyaluronic Acid

80
Q

What cell type organizes the ECM and helps cells attach to it (except the basal lamina)?

A

Fibronectin

81
Q

Bullous Pemphigoid (Junctional EB) is a blistering disorder involving which cell junction?

A

Hemidesmosomes, mutation in protein, laminins, or integrins

82
Q

____ is an autoimmune disorder involving desmosomal cadherins

A

Pemphigus vulgaris

83
Q

What proteins bind desmosomes and adherins junctions?

A

Cadherins

84
Q

What intracellular anchor proteins help desmosomes bind cadherins?

A

Desmoplankin and plakoglobin

85
Q

What are the linker proteins used by adherins junctions?

A

Catenins

86
Q

Desmosomes bind to ____ in the cell, whereas adherins junctions bind to ___.

A

Intermediate filaments, F-actin

87
Q

To produce the weak adhesion needed to begin lymphocyte rolling, ___ on activated epithelial cells bind oligosaccharides on WBS’s.

A

Selectins

88
Q

The binding of selectins and oligosaccharides between endothelial cells and WBC’s activates the ____ on WBC’s, which bind ___ on endothelial cells, creating a strong adhesion.

A

Integrin, iCAM

89
Q

WBC migration into tissue is known as:

A

Diapedesis

90
Q

A tell-tale sign of OI is:

A

Blue sclera

91
Q

The vascular type of Ehlers-Danlos Syndrome, Type IV, is due to a mutation in which type of collagen?

A

Collagen type III

92
Q

What type of collagen forms anchoring proteins?

A

Collagen type VII

93
Q

Name 4 treatment options for DMD currently in clinical trials

A

Stem cell therapy with mini-dystrophin
Up regulation of utrophin (fetal homolog)
Gene transfer and exon skipping
Ataluren (Translarna)- binds ribosome, skips nonsense mutations

94
Q

What two fiber types are present in the ECM?

A

Collagen and elastin

95
Q

What is ground substance made up of?

A

Proteoglycans (protein and GAGs)

Glycoproteins (sugars and protein)

96
Q

What is the purpose of glycoproteins in the ECM?

A

Adhesion

97
Q

What is the purpose of proteoglycans in the ECM?

A

Resist compression and full spaces

98
Q

What is the purpose of collagen in the ECM?

A

Strengthen, resist stretching, organizes ECM

99
Q

What are three types of glycoproteins?

A

Fibronectin, laminin, entactin

100
Q

What are the two functions of the ECM in connective tissue?

A

Scaffold to stabilize cell structure and resist forces

Influence cell behavior; survival, proliferation, migration, shape

101
Q

The majority of collagen is a repeating structure of what three amino acids, which form a chain then twist together into a triple helix?

A

Glycine, Lysine (+hydroxylysine), and Proline (+hydroxyproline)

102
Q

Which amino acid in collagen is small and allows H bonding between its backbone and the adjacent helix?

A

Glycine

103
Q

What two amino acids or derivatives make up ~25% of collagen and form kinks to help helix formation?

A

Proline and hydroxyproline

104
Q

Collagen chains are synthesized as longer precursors called:

A

Preprocollagens

105
Q

What is the purpose of procollagen propeptide domains?

A

Enhance helix formation and prevent premature fibril formation

106
Q

Triple helix formation starts at which terminus?

A

C

107
Q

Hydroxyproline is only found where?

A

Collagen and elastin

108
Q

The enzymes that convert proline and lysine to hydroxyproline and hydroxylysine require:

A

Vitamin C (ascorbic acid)

109
Q

Lysines and hydroxylysines are deaminated by _____, causing spontaneous fibril formation due to reactive aldehyde

A

Lysyl oxidase (extracellular)

110
Q

Collagen types I, II, III, and V are:

A

Fibrillar

111
Q

Collagen type I is found in:

A

Bone and skin

112
Q

Collagen type II is found in:

A

Cartilage

113
Q

Collagen type III is found in:

A

Vessels

114
Q

Collagen types IV and X are:

A

Sheet (Network) forming collagens

115
Q

Collagen types VI, IX, and XII are:

A

Connecting collagens (FACITs)

116
Q

Collagen type VII is an:

A

Anchoring collagen

117
Q

Which collagen is only found in the basal lamina?

A

IV

118
Q

Which collagen is important for anchoring the epidermis to the dermis?

A

Collagen type VII

119
Q

What is the purpose of matrix metalloproteinases (MMPs)?

A

Digest collagen so it may be remodeled

120
Q

Zinc dependent enzymes degrade:

A

The ECM via increasing MMP activity

121
Q

Elastin is rich in what two amino acids?

A

Proline and glycine

122
Q

What protein is associated with elastin and is important in assembly and integrity of elastin?

A

Fibrillin

123
Q

Alpha1-antitrypsin is an inhibitor of:

A

Elastase

124
Q

Uninhibited destruction of elastic fibers by elastase resulting in COPD (emphysema) is a result of mutation/deficiency in:

A

a1-AT

125
Q

A barrel chest and dyspnea are symptoms of:

A

Emphysema (COPD)

126
Q

What are the five glycosaminoglycans (GAGs)?

A
Hyaluronan
Dermatin sulfate
Chondroitin sulfate
Keratin sulfate
Heparan sulfate (heparin)
127
Q

Which GAG does not have a sulfate group, forms huge chains, is synthesized on the basal epithelial surface, and does not link to a core protein and form a proteoglycan?

A

Hyaluronan

128
Q

MOST glycosylation occurs in:

A

The golgi apparatus

129
Q

What are the four components of the basal lamina?

A

Type IV collagen
Laminin
Entactin/indigent
HSPG (perlican)

130
Q

What adhesive glycoprotein organizes basal lamina assembly by binding cell membrane receptors (integrins, dystroglycan)?

A

Laminin

131
Q

What are the three components of the ECM?

A
Fibrous structural proteins(collagen, elastin, fibrillin)
Adhesive glycoprotein (fibronectin, laminin, entactin(
Gel of proteoglycans and hyaluronan
132
Q

The ECM is arranged into two general organizations:

A

The basal lamina and the interstitial matrix

133
Q

What adaptors are used to link integrins with actin in a focal adhesion?

A

Vinculin and talin

134
Q

What adaptor protein is used to join integrin with intermediate filaments in a hemidesmosome?

A

Plectin

135
Q

What are the transmembrane adhesion proteins used in tight junctions?

A

Claudine and occludin

136
Q

Diffusion of substance across the epithelial layer between cells is what pathway?
What modulates this pathway, as well as determining epithelial cell polarity?

A

Paracellular, tight junctions

137
Q

What are the linker proteins used in Desmond omega?

A

Desmoplakin and plakoglobin

138
Q

Bullous pemphigoid is attack of _____, whereas pemphigus vulgaris is an attack on_______.

A

Hemidesmosomes, desmosomes

139
Q

In gap junctions, 6 ____ form ______, and two of these form a channel

A

Connexin subunits, connexon

140
Q

A disorder in gap junction connexon-32 in Schwann cells resulting in demyelination is called:

A

Charcot-Marie-Tooth (CMT) disease

141
Q

Activation of _____ on endothelial cells trigger leukocyte rolling

A

Selectins

142
Q

Leukocyte tolling triggers activation of _____ which binds iCAM on endothelial cells in a strong adhesion

A

Integrins

143
Q

Immigration of WBCs into tissue is called:

A

Diapedesis

144
Q

Types I and I EDS present with joint hyper mobility and hyperextensible skin due to mutation in:

A

Collagen types I/V

145
Q

Type IV EDS, presenting with vascular problems, involves a mutation in:

A

Collagen type III

146
Q

Type VI EDS involving ocular fragility and kyphosis is due to a mutation in _____ causing collagen instability.

A

Lysyl hydroxylase

147
Q

Type VII EDS, presenting solely as joint hypermobility, is due to a defect in:

A

Converting procollagen I to collagen I