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Cell Bio > Gap Junctions and Cell Signaling > Flashcards

Gap Junctions and Cell Signaling Flashcards

1
Q

What two types of tissue are cell junctions found to be abundant?

A

Epithelial and Connective

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2
Q

Attachments between cells are made by _____-_____ junctions

A

Cell-Cell

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3
Q

Cells are anchored onto the basal lamina through ____-____ junctions

A

Cell-Matrix

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4
Q

What are the main types of cell-cell junctions?

A

Tight Junctions
Cell-Cell Anchoring
Gap Junctions

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5
Q

What are the two forms of cell-cell anchoring junctions?

A

Adherens junctions
Desmosomes

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6
Q

What are the types of cell-matrix junctions?

A

Actin linked cell-matrix junctions
Hemidesmosomes

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7
Q

Channel forming junctions are an example of what type of cell-cell junction?

A

Gap Junction

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8
Q

What are considered the communicating junctions?

A

Gap Junctions

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9
Q

What junctions are found more lateral/apical?

A

Tight Junctions

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10
Q

What junctions are more basal/bottom of cell?

A

Desmosomes

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11
Q

Which of the following is NOT a characteristic of tight junctions?
a) Seals intercellular space from luminal environment
b) Seal is not absolute
c) Permeability varies
d) Located on basal aspect

A

D) It is located on the APICAL not the basal aspect

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12
Q

Which of the following would contain tight junctions?
a) Intestinal mucosa
b) bladder
c) respiratory tract
d) All of the above

A

d) all of the above

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13
Q

True or False
Tight junctions serve as selective permeability barriers for transcellular transport

A

False - it serves as selective barriers for PARACELLULAR transport

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14
Q

What two proteins make up tight junctions?
a) Fibronectin and laminin
b) Elastin and cadherin
c) claudin and occludin
d) none of the above

A

c) claudin and occludin

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15
Q

True or False
The lipid bilayer can transmit large forces from cell to cell and cell-ECM

A

False - it is too flimsy and needs anchoring junctions

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16
Q

Where would anchoring junctions likely be found?
a) small intestine
b) heart
c) skeletal muscle
d) epidermis
e) B, C, D

A

e) B, C, D

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17
Q

Cell-Cell Anchoring junctions rely on transmembrane adhesion proteins called:
a) Calmodulin
b) Integrins
c) Fibronectin
d) Cadherins

A

d) cadherins

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18
Q

These function as “flexible spot-welds” and form strong structural connections between cells

A

Cadherins

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19
Q

True or False
Cadherins are calcium dependent adhesion proteins

A

True

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20
Q

What junction connects one actin filament bundle in one cell to the next?

A

Adherens Junctions

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21
Q

Which of the following statements are true of adherens junctions?
a) Provide anchorage for cytoskeleton
b) Help model shape of multicellular structures
c) Guide organization of developing tissues
d) Located more basal than tight junctions
e) All of the above

A

e) all of the above

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22
Q

What junctions connect intermediate filaments in one cell to the next?

A

Desmosomes

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23
Q

True or False
Desmosomes connect actin bundle of one cell to the next

A

False - Adherens junctions connect actin bundles, Desmosomes connect intermediate filaments

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24
Q

What is the main function of desmosomes?

A

Provide mechanical strength

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25
What are the cadherin proteins in desmosomes?
Desmoglein and Desmocollin
26
True or False Desmosomes are likely to be found in tissue under stress/stretches (i.e. skin, muscles, intestines, stomach, bladder)
True
27
What junctions allow the passage of small hydrophilic molecules from cell to cell?
Gap Junctions
28
True or False The gap junctions allow for a large gap between cells
False - the gap is narrow
29
Which of the following can pass through gap junctions? a) Ions b) glucose c) second messengers d) all of the above
d) all of the above
30
What type of junction is important in tissues containing electrically excitable cells? a) Tight junctions b) Gap junctions c) Adherin junctions d) Desmosomes
b) Gap junctions
31
In what junctions do membrane proteins from adjacent cells line up to form a channel?
Gap Junctions
32
What junctions depend on integrins? a) Cell-Cell b) Desmosomes c) Cell-Matrix d) all of the above
C) cell-matrix anchoring junctions
33
What are the transmembrane proteins that bridge cell-matrix interactions?
Integrins
34
Which of the following is true of integrins? a) Found in electrically excitable tissue b) Ca dependent c) Can influence almost any aspects of cell behavior d) All of the above
C) Can influence almost any cell behavior (ex: embryonic development, blood clotting, migration, proliferation, signaling, survival)
35
What type of junction anchors actin-filaments in the cell to the ECM?
Actin linked cell-matrix junction (focal adhesion)
36
True or False Actin-Linked junctions can be small and transient OR large and durable
True
37
What anchor intermediate filaments in a cell to the ECM? a) Desmosomes b) Hemidesmosomes c) Actin filaments d) Desmogleins
b) Hemidesmosomes
38
True or False Instead of desmogleins, hemidesmosomes use integrins
True
39
What act as adhesions for epithelial cells to the basement membrane?
Hemidesmosomes
40
Which of the following is an incorrect statement about ligands? a) Enzymatic properties b) Not metabolized to useful products c) Do not act as intermediates d) All are true statements
a) Enyzmatic properties - They do NOT have enzymatic properties. Their only function is to change receptor properties.
41
The following are examples of first messengers except: a) Proteins b) Steroids c) Neurotransmitters d) Hormones e) All of the above are examples
e) all of the above
42
True or False A receptor is a protein that receives chemical signals from only outside the cell
False A receptor receives signals from outside OR inside the cell
43
True or False Effector proteins elicit cellular responses to signaling molecules
True
44
If the cellular response to a particular signaling molecule is shape change, the ______ ______ would be enzymes that remodel the cytoskeleton.
effector proteins
45
What is/are the ligands for cholinergic receptors? a) Catecholamines b) Dopamine c) Acetylcholine d) Epinephrine
c) Acetylcholine
46
What is/are the ligands for adrenergic receptors? a) Catecholamines b) Acetylcholine c) Dopamine d) Norepinephrine e) Epinephrine f) All but B
f) All but B
47
True or False Nicotinic and Muscarinic are cholinergic receptors
True
48
True or False alpha 1, alpha 2 and beta are cholinergic receptors
False - they are adrenergic receptors
49
Cell surface receptors are hydrophilic or hydrophobic signal molecules?
Hydrophobic - they can not go through the membrane so they bind to the surface.
50
Intracellular receptors can be located where? a) Cytosol b) Cytoplasm c) Nucleus d) a and c e) b and c
e) b and c
51
All of the following are cell surface receptors EXCEPT: a) Metabotropic b) Ionotropic c) Ligand Gated d) Nuclear receptors
d) Nuclear receptors
52
Which of the following is NOT a water-soluble second messenger? a) Ca2+ b) DAG c) IP3 d) cAMP
b) DAG - it is a lipid, therefore not water soluble
53
True or false A protein phosphatase adds a phosphate group to the protein
False - it removes a phosphate group, protein KINASE adds a phosphate
54
What serves as a molecular switch? a) G proteins b) GPCR c) Integrins d) PIP2
a) G Proteins
55
What is the prototype for all GPCRs? a) Beta blockers b) B-adrenergic c) G proteins d) None of the above
b) B-adrenergic receptors
56
What activates the G-protein alpha subunit? a) GDP b) GTP c) Both
c) Both GDP and GTP
57
What is the primary role of GAPs? a) Stimulate G-protein activation b) Stimulates GTP-ase activity c) Reactivates GPCR after desensitization
b) Stimulates GTP-ase activity - causing rapid inactivation of G protein
58
What converts ATP to cAMP? a) GTPase b) ADP c) Adenylate Cyclase d) PKA
c) Adenylate Cyclase
59
What activates PKA? a) Binding of cAMP b) Adenylate Cyclase c) GTPase d) None of the above
a) Binding of cAMP
60
True or False cAMP is inactivated by PDE
True
61
What catalyzes the formation of cAMP? a) GTP-ase b) PKA c) GDP/GTP d) Adenylate Cyclase
d) Adenylate Cyclase
62
True or False Phosphorylation of cellular proteins by PKA cause cellular response
True
63
Which of the following is a correct statement? a) cAMP allosterically activates PKA b) PKA has anabolic subunits c) Epinephrin binds to cholinergic receptors d) All are correct statements
a) cAMP allosterically activates PKA
64
Which of the following is a ligand that activates Gi protein? a) Epinephrin b) Glucagon c) Somatostatin d) ACTH
c) Somatostatin
65
All of the following are components of PIP2 pathway except: a) PKC b) Gi c) Phospholipase C d) DAG e) IP3
b) Gi
66
Which of the following is true regarding cAMP? a) Formed from ATP b) Formation is catalyzed by AC c) Cystolic cAMP is reduced by PDE d) All of the above
d) all of the above
67
Which of the following is directly responsible for converting ATP into cAMP? a) PKC b) PKA c) Gs d) Adenylate Cyclase
d) Adenylate Cyclase
68
Which of the following regulate B-adrenergic system by inactivating the pathway: a) Low concentration of epinephrin b) GTPase activity of G protein c) GAPs d) Desensitization e) All of the above
e) all of the above
69
What does GAP stand for? a) G alpha Protein b) GTPase Protein c) GPTase Activator Protein d) GPCR Activated Protein
C) GTPase Activator Protein
70
Which of the following statements is correct: a) BARK creates binding site for B-arr b) BARK stops interaction between receptor and G-protein c) B-arr binds to BARK d) B-arr is involved in activation of RTK
a) BARK creates binding site for B-arr
71
True or False Binding of BARK stops interaction between receptor and G protein
False - B-arr stops interaction
72
Which of the following is true? a) GAPS catalyze reaction to active G alpha subunit b) BARK phosphorylates receptor in order to deactivate G protein c) Barr initiates receptor sequestration to remove the receptor via endocytosis
C) Barr initiates receptor sequestration to remove receptor via endocytosis
73

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