MCB 3rd Unit 1 Flashcards
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
Name 2 actin cross-linking proteins which form filament webs/gels
Spectrin and filamin
26
Actin bundles and web-like organizations are initiated by ___ and stabilized by ____.
Nucleating proteins, cross-linking proteins
27
Name four non-muscle functions of actin
Microvilli
Stress fibers
Cell surface protrusions (cell migration)
Cytokinesis
28
Alpha-actinin is loosely packed and contractile, used for:
Stress fibers
29
Fimbrin is tightly packed and non-contractile, used for:
microvilli
30
How do actin stress fibers within the cell bind to ECM to allow movement?
Use integrin receptors at "focal adhesion" sites
31
What proteins at the cell surface activate nucleating proteins (arp 2/3 complex and formins)?
Rho GTPases
32
RhoGTPases located at the cell surface activate:
nucleating proteins
33
Which RhoGTPase is responsible for formation of lamellipodia?
rac
34
Which RhoGTPase is responsible for formation of filipodia?
cdc42
35
Which RhoGTPase is responsible for formation of stress fibers?
rho
36
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
Wiskott-Aldrich Syndrome
37
Name 3 drugs t hat can bind to actin filaments
Cytochalasins, plahhoidin, latrunculin
38
Thick filaments of myofibrils are made up of:
Hundreds of myosin II motor proteins
39
Thin filaments of myofibrils are made up of:
Actin filament with tropomyosin and tryponin complex
40
What protein links the actin cytoskeleton with the integral membrane glycoprotein complex that interacts with the ECM?
Dystrophin
41
Dystrophin links the actin cytoskeleton to which protein specifically?
Laminin-2
42
Muscle is repaired by which cell populations? Which does more?
Satellite cells and side population cells, satellite cells
43
What is a bloodwork flag for muscular damage?
Increased serum creatine kinase
44
What is the most severe type of muscular dystrophy and what is it's inheritance pattern?
Duchenne MD, X-linked
45
Which type of LGMD is AR?
LGMD 2
46
Congenital muscular dystrophy involves a mutation in what protein?
Laminin
47
What is an adhesive glycoprotein that anchors epithelial cells to the basal lamina via integrin receptors?
Laminin
48
What type of collagen binds with laminin to form scaffold for basal lamina?
Collagen type IV, “sheet forming” collagen
49
What two ECM proteins bind laminin and collagen IV, connecting the two networks?
Entactin and perlecan
50
GAG’s carry what charge? How does this attract water?
Negative charge attracts cations which attract water
51
In hyperglycemia, downregulation of ____ causes collagen glycosylation and cross-linking causing thickening of the GBM
HSPG
52
Integrin receptors bind to the ____ sequence of fibronectin/laminin
RGD
53
What type of fibronectin is made by the liver and circulates in the blood enhancing clotting?
Soluble plasma fibronectin
54
What type of fibronectin is formed on the cell surface and deposited in the ECM?
Insoluble fibronectin fibrils
55
Integrins bind laminin in the _____ and fibronectin in the ____.
Basal lamina, connective tissue
56
In _____, integrins bind keratin intermediate filaments in the cell cia adaptor proteins (plectin) and to laminin in the basal lamina
Hemidesmosomes
57
In _______ adhesions, integrins bind to actin stress fibers via adaptor proteins (vinculin and talin), and to fibronectin in the connective tissue
Focal adhesions
58
______ cross links actin stress fibers
Alpha-actinin
59
The purpose of focal adhesions is:
Motility
60
Fillipodia are for ____, while lamellopodium are for _____.
Sensing, movement
61
What GTPase rearranges actin to stretch into lamellopodium? Which mediates formation of stress fibers and new focal contacts?
RAC, RHO
62
What GTPase regulates filopodia protrusion?
Cdc42
63
What are the four types of cell-cell junctional complexes?
Tight
Adherins
Desmoses
Gap
64
An adhesive protein that binds to sugars instead of other proteins is a:
Lectin
65
A disease caused by absence of platelet integrin complex (aka glycoprotein Ilb-IIIa) and consequential failure of platelet aggregation
Glanzmann Thrombasthenia
66
Articular and hyaline cartilage are formed from which type of collagen
Type II collagen forms articular and hyaline cartilage
67
Constitutive activation of the RTK FGFR3 inhibits proliferation of what cell type, and thus causes what condition?
Chondrocytes. achondroplasia
68
What type(s) of collagen form sheets?
Collagen types IV and X
69
What type(s) of collagen form anchoring fibrils?
Collagen type VII
70
What are the fibrillar collagens?
Collagen types I, II, III, and V
71
What are the Fibril Associated (Networking) Collagens with Interrupted Triple helices (FACIT's)?
Collagen type VI, IX, and XII
72
MMP-1 degrades collagen type ___, while MMP-2 is a collagenase for type____.
I, IV
73
Osteogenesis Imperfecta is associated with what type(s) of collagen?
Collagen type I
74
Ehlers-Danlos Syndrome is associated with what type(s) of collagen?
Collagen types I, III, and V
75
Alport Syndrome is associated with what type(s) of collagen?
Collagen type IV
76
Goodpasture Syndrome is associated with auto-antibodies to what type(s) of collagen?
Collagen type IV
77
Dystrophic Epidermolysis bullosa is associated with what type(s) of collagen?
Collagen Type VII
78
Inherited Epidermolysis Bullosa Simplex is caused by a mutation in ____
Keratin 5 or 14
79
What GAG forms the central core of proteoglycan aggregates?
Hyaluronic Acid
80
What cell type organizes the ECM and helps cells attach to it (except the basal lamina)?
Fibronectin
81
Bullous Pemphigoid (Junctional EB) is a blistering disorder involving which cell junction?
Hemidesmosomes, mutation in protein, laminins, or integrins
82
____ is an autoimmune disorder involving desmosomal cadherins
Pemphigus vulgaris
83
What proteins bind desmosomes and adherins junctions?
Cadherins
84
What intracellular anchor proteins help desmosomes bind cadherins?
Desmoplankin and plakoglobin
85
What are the linker proteins used by adherins junctions?
Catenins
86
Desmosomes bind to ____ in the cell, whereas adherins junctions bind to ___.
Intermediate filaments, F-actin
87
To produce the weak adhesion needed to begin lymphocyte rolling, ___ on activated epithelial cells bind oligosaccharides on WBS's.
Selectins
88
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.
Integrin, iCAM
89
WBC migration into tissue is known as:
Diapedesis
90
A tell-tale sign of OI is:
Blue sclera
91
The vascular type of Ehlers-Danlos Syndrome, Type IV, is due to a mutation in which type of collagen?
Collagen type III
92
What type of collagen forms anchoring proteins?
Collagen type VII
93
Name 4 treatment options for DMD currently in clinical trials
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
What two fiber types are present in the ECM?
Collagen and elastin
95
What is ground substance made up of?
Proteoglycans (protein and GAGs)
| Glycoproteins (sugars and protein)
96
What is the purpose of glycoproteins in the ECM?
Adhesion
97
What is the purpose of proteoglycans in the ECM?
Resist compression and full spaces
98
What is the purpose of collagen in the ECM?
Strengthen, resist stretching, organizes ECM
99
What are three types of glycoproteins?
Fibronectin, laminin, entactin
100
What are the two functions of the ECM in connective tissue?
Scaffold to stabilize cell structure and resist forces
| Influence cell behavior; survival, proliferation, migration, shape
101
The majority of collagen is a repeating structure of what three amino acids, which form a chain then twist together into a triple helix?
Glycine, Lysine (+hydroxylysine), and Proline (+hydroxyproline)
102
Which amino acid in collagen is small and allows H bonding between its backbone and the adjacent helix?
Glycine
103
What two amino acids or derivatives make up ~25% of collagen and form kinks to help helix formation?
Proline and hydroxyproline
104
Collagen chains are synthesized as longer precursors called:
Preprocollagens
105
What is the purpose of procollagen propeptide domains?
Enhance helix formation and prevent premature fibril formation
106
Triple helix formation starts at which terminus?
C
107
Hydroxyproline is only found where?
Collagen and elastin
108
The enzymes that convert proline and lysine to hydroxyproline and hydroxylysine require:
Vitamin C (ascorbic acid)
109
Lysines and hydroxylysines are deaminated by _____, causing spontaneous fibril formation due to reactive aldehyde
Lysyl oxidase (extracellular)
110
Collagen types I, II, III, and V are:
Fibrillar
111
Collagen type I is found in:
Bone and skin
112
Collagen type II is found in:
Cartilage
113
Collagen type III is found in:
Vessels
114
Collagen types IV and X are:
Sheet (Network) forming collagens
115
Collagen types VI, IX, and XII are:
Connecting collagens (FACITs)
116
Collagen type VII is an:
Anchoring collagen
117
Which collagen is only found in the basal lamina?
IV
118
Which collagen is important for anchoring the epidermis to the dermis?
Collagen type VII
119
What is the purpose of matrix metalloproteinases (MMPs)?
Digest collagen so it may be remodeled
120
Zinc dependent enzymes degrade:
The ECM via increasing MMP activity
121
Elastin is rich in what two amino acids?
Proline and glycine
122
What protein is associated with elastin and is important in assembly and integrity of elastin?
Fibrillin
123
Alpha1-antitrypsin is an inhibitor of:
Elastase
124
Uninhibited destruction of elastic fibers by elastase resulting in COPD (emphysema) is a result of mutation/deficiency in:
a1-AT
125
A barrel chest and dyspnea are symptoms of:
Emphysema (COPD)
126
What are the five glycosaminoglycans (GAGs)?
```
Hyaluronan
Dermatin sulfate
Chondroitin sulfate
Keratin sulfate
Heparan sulfate (heparin)
```
127
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?
Hyaluronan
128
MOST glycosylation occurs in:
The golgi apparatus
129
What are the four components of the basal lamina?
Type IV collagen
Laminin
Entactin/indigent
HSPG (perlican)
130
What adhesive glycoprotein organizes basal lamina assembly by binding cell membrane receptors (integrins, dystroglycan)?
Laminin
131
What are the three components of the ECM?
```
Fibrous structural proteins(collagen, elastin, fibrillin)
Adhesive glycoprotein (fibronectin, laminin, entactin(
Gel of proteoglycans and hyaluronan
```
132
The ECM is arranged into two general organizations:
The basal lamina and the interstitial matrix
133
What adaptors are used to link integrins with actin in a focal adhesion?
Vinculin and talin
134
What adaptor protein is used to join integrin with intermediate filaments in a hemidesmosome?
Plectin
135
What are the transmembrane adhesion proteins used in tight junctions?
Claudine and occludin
136
Diffusion of substance across the epithelial layer between cells is what pathway?
What modulates this pathway, as well as determining epithelial cell polarity?
Paracellular, tight junctions
137
What are the linker proteins used in Desmond omega?
Desmoplakin and plakoglobin
138
Bullous pemphigoid is attack of _____, whereas pemphigus vulgaris is an attack on_______.
Hemidesmosomes, desmosomes
139
In gap junctions, 6 ____ form ______, and two of these form a channel
Connexin subunits, connexon
140
A disorder in gap junction connexon-32 in Schwann cells resulting in demyelination is called:
Charcot-Marie-Tooth (CMT) disease
141
Activation of _____ on endothelial cells trigger leukocyte rolling
Selectins
142
Leukocyte tolling triggers activation of _____ which binds iCAM on endothelial cells in a strong adhesion
Integrins
143
Immigration of WBCs into tissue is called:
Diapedesis
144
Types I and I EDS present with joint hyper mobility and hyperextensible skin due to mutation in:
Collagen types I/V
145
Type IV EDS, presenting with vascular problems, involves a mutation in:
Collagen type III
146
Type VI EDS involving ocular fragility and kyphosis is due to a mutation in _____ causing collagen instability.
Lysyl hydroxylase
147
Type VII EDS, presenting solely as joint hypermobility, is due to a defect in:
Converting procollagen I to collagen I
