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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
Q

FOCAL ADHESIONS and HEMODESMOSOMES have transmembrane adhesion proteins that belong to the ________ family

A

FOCAL ADHESIONS and HEMIDESMOSOMES have transmembrane adhesion proteins that belong to the INTEGRIN family

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26
Q

Adherens junctions are _____ junctions found primarily in epithelia

A

Adherens junctions are CELL-TO-CELL junctions found primarily in epithlia

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27
Q

Adherens Junctions form a _______ just below the tight junction

A

Adherens junctions form a CONTINUOUS ADHESION BELT just below the tight junction

28
Q

Adherens junction transmembrane proteins are ________

A

Adherens junction transmembrane proteins are called CADHERINS

29
Q

Adherens junctions connect bundles of _________

A

Adherens junctions connect bundles of ACTIN FILAMENTS - CONTRACTILE

30
Q

Adherens junctions are necessary for ________ formation and _______ formation in morphogenesis

A

Adherens junctions are necessary for TIGHT JUNCTION formation and EPITHELIAL TUBE formation in morphogenesis

31
Q

Adherens junctions are built from _____ and _____

A

Adherens junctions are built from CADHERINS and CATENINS

32
Q

Cadherins are transmembrane proteins whose extracellular segment bind to ______ and whose intracellular segments bind to _______

A

Cadherins are transmembrane proteins whose extracellular segment bind to EACH OTHER and whose intracellular segments bind to CATENINS

33
Q

_______ are cell-cell junctions that “rivet” cells together

A

DESMOSOMES are cell-cell junctions that “rivet” cells together

34
Q

Desmosomes are primarily found in ____ and ____ cells

A

Desmosomes are primarily found in EPITHELIA and MUSCLE cells

35
Q

Desmosomes contribute to tissue ____ and ____

A

Desmosomes contribute to tissue STRENGTH and DURABILITY

36
Q

Desmosome transmembrane proteins are ______

A

Desmosome transmembrane proteins are CADHERINS

37
Q

___________ attach junctional epithelium to the tooth enamel

A

HEMIDESMOSOMES attach junctional epithelium to the tooth enamel

38
Q

Hemidesmosomes resemble half-desmosomes, but bind cells _____

A

Hemidesmosomes resemble half-desmosomes, but bind cells TO THE ECM

39
Q

Hemidesmosome transmembrane adhesion proteins are ______

A

Hemidesmosome transmembrane adhesion proteins are INTEGRINS

40
Q

In patients with Chronic Periodontitis, what is the cause pertaining to cell junctions?

A

In patients with Chronic Periodontitis, Hemidesmosomes are missing integrins

41
Q

In patients with chronic periodontitis, they often exhibit changes in abundance of _______, ______, ________

A

In patients with chronic periodontitis, they often exhibit changes in abundance of Type IV collagen, lamanins, and fibronectins.

42
Q

Necrotizing Ulcerative Periodontitis is caused by changes in epithelial abundance of ______ and _______

A

Necrotizing Ulcerative Periodontitis is caused by changes in epithelial abundance of INTEGRINS and LAMININS

43
Q

Focal Adhesions are ______-type junctions that link the cell _________ to the ECM

A

Focal adhesions are SPOT-type junctions that link the cell CYTOSKELETON to the ECM

44
Q

Why are focal adhesions described as being “complex”

A

Focal adhesions are “complex” because they can contain as many as 100 different proteins (including structural proteins, kinases, and phosphotases)

45
Q

Focal adhesions are said to be “Dynamic” because they can _____, _____, or ____ in response to intracellular or extracellular signals

A

Focal adhesions are said to be “Dynamic” because they can FORM, CHANGE, or DISAPPEAR in response to intracellular and extracellular signals

46
Q

Focal Adhesions transmit _______ to the cell interior via integrin receptors

A

Focal adhesions transmit EXTERNAL MECHANICAL SIGNALS to the cell interior via integrin receptors

47
Q

Aberrant _______ proteins are involved in tumor development and cancer metastasis

A

Aberrant FOCAL ADHESION proteins are involved in tumor development and cancer metastasis

48
Q

Focal adhesions are important in 4 cell functions, _____, _____, _____, and ______, and in orthodontic tooth movement

A

Focal adhesions are important in cell MIGRATION, MOTILITY, DIFFERENTIATION, and PROLIFERATION, and in orthodontic tooth movement

49
Q

Focal adhesions transmit external mechanical signals via __________.

A

Focal adhesions transmit external mechanical signals via INTEGRIN RECEPTORS

50
Q

Via what pathways/channels do integrins undergo signal transduction?

A

Integrins undergo signal transductions in…

  1. Adenylate cyclase pathway
  2. Inositol phosphate pathway
  3. Mechanosensitive ion channels (and other protein cell membranes)
51
Q

__________ have channels, called connexons

A

Gap Junctions have channels called connexons

52
Q

Gap junctions are _______ junctions

A

Gap junctions are COMMUNICATING junctions

53
Q

Gap junctions are found in nearly all cells except _________ and _______

A

Gap junctions are found in nearly all cells except SKELETAL MUSCLE and BLOOD CELLS

54
Q

Gap junctions allow _____ and ______ to pass directly from cell to cell

A

Gap junctions allow SMALL MOLECULES and ELECTRICAL CHARGES to pass directly from cell to cell

55
Q

Channels, called connexones, are ____ (shape/number) of _______ proteins

A

Channels, called connexons, are HEXAMERS of CONNEXIN proteins

56
Q

In gap junctions, connexon permeability varies with the ______ and ______ of connexins present

A

In gap junctions, connexon permeability varies with the IDENTITY and COMBINATIONS of connexins present

57
Q

Gap junction permeability can be regulated by intracellular signals, _____ and _____, and by extracellular signals

A

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
Q

Like within the heart, gap junctions allow the cells of a given tissue to function together _____ and in a ______ fashion

A

Like within the heart, gap junctions allow the cells of a given tissue to function together QUICKLY and in a COORDINATED fashion

59
Q

Gap junctions have 2 types of coupling functions, name them.

A

Gap junction coupling function includes….

  1. Electrical coupling
  2. Metabolic coupling
60
Q

What are the 4 primary functions of Gap junctions?

A

Gap junction functions are…

  1. Signal transmission
  2. Coordination of early embryogenesis
  3. Metabolic Coupling
  4. Electrical coupling
61
Q

Gap junctions exhibit electrical coupling….what is electrical coupling?

A

Electrical coupling: Action potentials spread rapidly from cell-to-cell (such as in heart muscle and smooth muscles of the GI tract)

62
Q

Signal transduction in hepatocytes occurs when _______ is converted to glucose when sympathetic nerve signals release _________

A

Signal transduction in hepatocytes occurs when GLYCOGEN is converted to glucose when sympathetic nerve signals release NOREPINEPHARINE

63
Q

In one sentence, summarize the physical function of tight junctions

A

Tight junctions seal neighboring cells together in an epithelial sheet to prevent leakage of molecules between them

64
Q

In one sentence, summarize the physical function of adherens junctions

A

Adherens junctions join an actin bundle in one cell to a similar bundle in a neighboring cell

65
Q

In one sentence, summarize the physical function of desmosomes

A

Desmosomes join the intermediate filaments in one cell to those in a neighbor

66
Q

In one sentence, summarize the physical function of gap junctions

A

Gap junctions allow the passage of small water-soluble ions and molecules

67
Q

In one sentence, name the physical function of hemidesmosomes

A

Hemidesmosomes anchor intermediate filament in a cell to the basal lamina

Biochem 6200 (4 decks)

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