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Biochem 6200 > Mokrzan Study Guide (exam 3, pt 2 = Cell Junctions) > Flashcards

Mokrzan Study Guide (exam 3, pt 2 = Cell Junctions) Flashcards

1
Q

Define Cell Junctions

A

Cell Junctions are Specialized regions where cells are attached to each other and the ECM

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2
Q

______ tissues are particularly rich in cellular junctions

A

EPITHELIAL tissues are particularly rich in cellular junctions

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3
Q

Cell Junctions maintain ______ ______ structure

A

Cell Junctions maintain STABLE TISSUE structure

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4
Q

Cell Junctions enable cells to ______ _______ to their environment

A

Cell Junctions enable cells to RESPOND APPROPRIATELY to their environment

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5
Q

Cell Junctions ________ cells so they can function together

A

Cell Junction COORDINATE cells so they can function together

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6
Q

Cell Junction play a direct roll in 4 general cell processes. Name all 4.

A

Cell Junctions play a role in direct processes such as….

  1. Growth
  2. Healing
  3. Morphogenesis
  4. Development
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7
Q

There are 3 general/overarching types of cell junctions. Name all 3.

A

Three general/overarching types of cell junctions:

  1. Anchoring Junctions
  2. Tight Junctions
  3. Communicating Junctions
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8
Q

Tight Junctions are located ONLY in _______

A

Tight Junctions are located ONLY in EPITHELIAL TISSUES

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9
Q

Tight Junctions are ____ junctions found in all epithelia

A

Tight junctions are CELL-TO-CELL junctions found in all epithelia

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10
Q

Tight Junctions severely limit _________ between cells

A

Tight Junctions severely limit DIFFUSION OF SOLUTES between cells (limit intercellular permeability - many important small molecules must travel thru tight junction)

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11
Q

Tight Junctions maintain cell polarity via different protein components in the _____ and _____ membranes

A

Tight Junctions maintain cell polarity via different protein components in the APICAL and BASOLATERAL membranes

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12
Q

Tight Junctions are formed by _______ anchored in the membrane

A

Tight junctions are formed by SEALING STRANDS anchored in the membrane

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13
Q

Because each strand within a tight junction acts independently from the others, the efficiency of the junctions in preventing _______ increases with increasing number of strands

A

Because each strand within a tight junction acts independently from the others, the efficiency of the junctions in preventing ION PASSAGE increases with increasing number of strands

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14
Q

Tight junction proteins include _____ and _____

A

Tight junction proteins include CLAUDIN and OCCLUDIN

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15
Q

Tight junction permeability is determined by what 2 factors?

A

Tight junction permeability is determined by…

  1. The number of sealing strands
  2. The identity of the transmembrane proteins (occludin and claudin families)
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16
Q

_______ are required for active transport of solutes across the epithelial barrier

A

TIGHT JUNCTIONS are required for active transport of solutes across the epithelial barrier

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17
Q

Tight Junctions have two barrier functions. Name them.

A

Tight Junctions act as barriers by…

  1. Helping to maintain the polarity of cells by preventing the lateral diffusion if integral membrane proteins between apical and basolateral surfaces. (THIS AIMS TO PRESERVE TRANSCELLULAR TRANSPORT)
  2. Preventing the passage of molecules and ions thru the space between plasma membranes and adjacent cells, so material must actually enter the cells (by diffusion or active transport) in order to pass through the tissue.
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18
Q

All Tight Junctions are impermeable to __________ (and give one example)

A

All tight junctions are impermeable to MACROMOLECULES (like Glucose, which must use transporters to move across apical and basolateral surfaces)

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19
Q

________ bind cells to each other AND to the ECM

A

ANCHORING JUNCTIONS bind cells to each other AND the ECM

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20
Q

_______ and ______ are types of anchoring junctions that connect neighboring cells

A

ADHERENS JUNCTIONS and DESMOSOMES are types of anchoring junctions that connect neighboring cells

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21
Q

____ and ______ are types of anchoring junctions that bind cells to the ECM

A

FOCAL ADHESIONS and HEMIDESMOSOMES are types of anchoring junctions that bind cells to the ECM

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22
Q

________ are found in all tissues, especially those subject to mechanical stress

A

ANCHORING JUNCTIONS are found in all tissues, especially those subject to mechanical stress

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23
Q

What are the 4 types of Anchoring junctions?

A

4 types of anchoring junctions are…

  1. Adherens Junctions
  2. Desmosomes
  3. Hemidesmosomes
  4. Focal Adhesions
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24
Q

________ and _______ are types of anchoring junctions that have transmembrane proteins belonging to the CADHERIN family

A

ANCHORING JUNCTIONS and DESMOSOMES are types of anchoring junctions that have transmembrane proteins belonging to the CADHERIN family

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25
FOCAL ADHESIONS and HEMODESMOSOMES have transmembrane adhesion proteins that belong to the ________ family
FOCAL ADHESIONS and HEMIDESMOSOMES have transmembrane adhesion proteins that belong to the INTEGRIN family
26
Adherens junctions are _____ junctions found primarily in epithelia
Adherens junctions are CELL-TO-CELL junctions found primarily in epithlia
27
Adherens Junctions form a _______ just below the tight junction
Adherens junctions form a CONTINUOUS ADHESION BELT just below the tight junction
28
Adherens junction transmembrane proteins are ________
Adherens junction transmembrane proteins are called CADHERINS
29
Adherens junctions connect bundles of _________
Adherens junctions connect bundles of ACTIN FILAMENTS - CONTRACTILE
30
Adherens junctions are necessary for ________ formation and _______ formation in morphogenesis
Adherens junctions are necessary for TIGHT JUNCTION formation and EPITHELIAL TUBE formation in morphogenesis
31
Adherens junctions are built from _____ and _____
Adherens junctions are built from CADHERINS and CATENINS
32
Cadherins are transmembrane proteins whose extracellular segment bind to ______ and whose intracellular segments bind to _______
Cadherins are transmembrane proteins whose extracellular segment bind to EACH OTHER and whose intracellular segments bind to CATENINS
33
_______ are cell-cell junctions that "rivet" cells together
DESMOSOMES are cell-cell junctions that "rivet" cells together
34
Desmosomes are primarily found in ____ and ____ cells
Desmosomes are primarily found in EPITHELIA and MUSCLE cells
35
Desmosomes contribute to tissue ____ and ____
Desmosomes contribute to tissue STRENGTH and DURABILITY
36
Desmosome transmembrane proteins are ______
Desmosome transmembrane proteins are CADHERINS
37
___________ attach junctional epithelium to the tooth enamel
HEMIDESMOSOMES attach junctional epithelium to the tooth enamel
38
Hemidesmosomes resemble half-desmosomes, but bind cells _____
Hemidesmosomes resemble half-desmosomes, but bind cells TO THE ECM
39
Hemidesmosome transmembrane adhesion proteins are ______
Hemidesmosome transmembrane adhesion proteins are INTEGRINS
40
In patients with Chronic Periodontitis, what is the cause pertaining to cell junctions?
In patients with Chronic Periodontitis, Hemidesmosomes are missing integrins
41
In patients with chronic periodontitis, they often exhibit changes in abundance of _______, ______, ________
In patients with chronic periodontitis, they often exhibit changes in abundance of Type IV collagen, lamanins, and fibronectins.
42
Necrotizing Ulcerative Periodontitis is caused by changes in epithelial abundance of ______ and _______
Necrotizing Ulcerative Periodontitis is caused by changes in epithelial abundance of INTEGRINS and LAMININS
43
Focal Adhesions are ______-type junctions that link the cell _________ to the ECM
Focal adhesions are SPOT-type junctions that link the cell CYTOSKELETON to the ECM
44
Why are focal adhesions described as being "complex"
Focal adhesions are "complex" because they can contain as many as 100 different proteins (including structural proteins, kinases, and phosphotases)
45
Focal adhesions are said to be "Dynamic" because they can _____, _____, or ____ in response to intracellular or extracellular signals
Focal adhesions are said to be "Dynamic" because they can FORM, CHANGE, or DISAPPEAR in response to intracellular and extracellular signals
46
Focal Adhesions transmit _______ to the cell interior via integrin receptors
Focal adhesions transmit EXTERNAL MECHANICAL SIGNALS to the cell interior via integrin receptors
47
Aberrant _______ proteins are involved in tumor development and cancer metastasis
Aberrant FOCAL ADHESION proteins are involved in tumor development and cancer metastasis
48
Focal adhesions are important in 4 cell functions, _____, _____, _____, and ______, and in orthodontic tooth movement
Focal adhesions are important in cell MIGRATION, MOTILITY, DIFFERENTIATION, and PROLIFERATION, and in orthodontic tooth movement
49
Focal adhesions transmit external mechanical signals via __________.
Focal adhesions transmit external mechanical signals via INTEGRIN RECEPTORS
50
Via what pathways/channels do integrins undergo signal transduction?
Integrins undergo signal transductions in... 1. Adenylate cyclase pathway 2. Inositol phosphate pathway 3. Mechanosensitive ion channels (and other protein cell membranes)
51
__________ have channels, called connexons
Gap Junctions have channels called connexons
52
Gap junctions are _______ junctions
Gap junctions are COMMUNICATING junctions
53
Gap junctions are found in nearly all cells except _________ and _______
Gap junctions are found in nearly all cells except SKELETAL MUSCLE and BLOOD CELLS
54
Gap junctions allow _____ and ______ to pass directly from cell to cell
Gap junctions allow SMALL MOLECULES and ELECTRICAL CHARGES to pass directly from cell to cell
55
Channels, called connexones, are ____ (shape/number) of _______ proteins
Channels, called connexons, are HEXAMERS of CONNEXIN proteins
56
In gap junctions, connexon permeability varies with the ______ and ______ of connexins present
In gap junctions, connexon permeability varies with the IDENTITY and COMBINATIONS of connexins present
57
Gap junction permeability can be regulated by intracellular signals, _____ and _____, and by extracellular signals
Gap junction permeability can be regulated by intracelullar signals, Decrease in cytosolic pH and Large increase in cytosolic Ca2+ levels, and by extracellular signals
58
Like within the heart, gap junctions allow the cells of a given tissue to function together _____ and in a ______ fashion
Like within the heart, gap junctions allow the cells of a given tissue to function together QUICKLY and in a COORDINATED fashion
59
Gap junctions have 2 types of coupling functions, name them.
Gap junction coupling function includes.... 1. Electrical coupling 2. Metabolic coupling
60
What are the 4 primary functions of Gap junctions?
Gap junction functions are... 1. Signal transmission 2. Coordination of early embryogenesis 3. Metabolic Coupling 4. Electrical coupling
61
Gap junctions exhibit electrical coupling....what is electrical coupling?
Electrical coupling: Action potentials spread rapidly from cell-to-cell (such as in heart muscle and smooth muscles of the GI tract)
62
Signal transduction in hepatocytes occurs when _______ is converted to glucose when sympathetic nerve signals release _________
Signal transduction in hepatocytes occurs when GLYCOGEN is converted to glucose when sympathetic nerve signals release NOREPINEPHARINE
63
In one sentence, summarize the physical function of tight junctions
Tight junctions seal neighboring cells together in an epithelial sheet to prevent leakage of molecules between them
64
In one sentence, summarize the physical function of adherens junctions
Adherens junctions join an actin bundle in one cell to a similar bundle in a neighboring cell
65
In one sentence, summarize the physical function of desmosomes
Desmosomes join the intermediate filaments in one cell to those in a neighbor
66
In one sentence, summarize the physical function of gap junctions
Gap junctions allow the passage of small water-soluble ions and molecules
67
In one sentence, name the physical function of hemidesmosomes
Hemidesmosomes anchor intermediate filament in a cell to the basal lamina

Biochem 6200 (4 decks)

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