Lecture 20: Cell Junctions

Question 1

cell junctions (def.)

Answer 1

Specialized contact sites linking cells with each other and to extracellular matrix

Question 2

cell junctions are important for what type of cells?

Answer 2

epithelial and endothelial cells

Question 3

Changes in physiological conditions can affect _____ of cell junctions

Answer 3

the assembly and stability

Question 4

mechanical stresses are transmitted from cell to cell by ______

Answer 4

cytoskeletal filaments anchored to cell-matrix and cell-cell adhesion sites

Question 5

extracellular matrix directly bears _____

Answer 5

mechanical stresses of tension and compression

Question 6

cell junctions are modified extensively during ___

Answer 6

oncogenesis (process of cell becoming cancerous)

Question 7

Cancer cells with modified cell junctions become _____ and are able to ____

Answer 7

motile
invade other tissues

Question 8

cell junctions are important for ______

Answer 8

anchoring
cell-cell communication
maintaining cellular barriers and polarity

Question 9

tight junction seals ___

Answer 9

gap between epithelial cells

Question 10

adherens junction connects ___

Answer 10

actin filament bundle in one cell with that in the next cell

Question 11

desmosome connects ______

Answer 11

intermediate filaments in one cell with that in the next cell

Question 12

gap junction allows the ____

Answer 12

passage of small water-soluble molecules from cell to cell

Question 13

actin-linked cell-matrix junction anchors _____

Answer 13

actin filaments in cell to extracellular matrix

Question 14

hemidesmosome anchors ____

Answer 14

intermediate filaments in cell to extracellular matrix

Question 15

Two types of proteins associated with cell junctions

Answer 15

-intracellular adaptor proteins (which connect to cytoskeletal filaments) a.k.a peripheral membrane proteins
-transmembrane adhesion proteins

Question 16

other cofactors of proteins associated with cell junctions

Answer 16

calcium

Question 17

calcium in cell junction is associated with _____

Answer 17

the ectodomain of the transmembrane protein

Question 18

ectodomain (def.)

Answer 18

domain of a membrane protein that extends into the extracellular space

Question 19

removing Ca+ with a chelating agent will have this effect on cell junctions?

Answer 19

disrupts the interactions between cells

Question 20

gap junction are ____ to allow ____

Answer 20

small direct channels between two cells
ions to pass for cell communication

Question 21

gap junctions are not a _____; what can’t pass?

Answer 21

tunnel
proteins

Question 22

Tight junctions regulate ____ transport

Answer 22

paracellular transport (fence function)

Question 23

Tight junctions provide _______ on either side of _____

Answer 23

selective barrier for extracellular fluids
epithelia (gut) or endothelia (blood vessel)

Question 24

Tight junctions form this in the brain?

Answer 24

blood-brain barrier

Question 25

Tight junctions regulates _____permeability

Answer 25

paracellular

Question 26

paracellular permeability (def.)

Answer 26

movement of molecules across epithelium between cells

Question 27

the effectiveness of barrier varies depending on ____

Answer 27

type of epithelium

Question 28

Tight junctions restricts ____ between _____which is essential for _____

Answer 28

diffusion of proteins/lipids apical and basolateral membranes polarity

Question 29

Tight junctions are important for ______ in gut

Answer 29

selective nutrient uptake

Question 30

transport of this nutrient requires tight seal between epithelial cells?

Answer 30

glucose

Question 31

Tight junctions are _____ and can allow _____ through blood vessels

Answer 31

dynamic immune cells to move

Question 32

TJs appear as a network of ____ that completely encircles _____

Answer 32

fibrils apical end of cell

Question 33

Fibrils creates a ____

Answer 33

labyrinth that ensures low permeability

Question 34

The purification of fibrils requires ____

Answer 34

monoclonal antibodies

Question 35

antibodies production in the lab method

Answer 35

1) antigen injected into mouse 2) animal will start generating antibodies for antigen in serum 3)serum will have mixture of different antibodies to same antigen (may react with different regions of antigen)

Question 36

antibodies production for tight junction in the lab method

Answer 36

1)"purify" tight junctions 2) same technique 3) different antibodies produced for different proteins that make up tight junctions

Question 37

polyclonal antibodies can recognize _____

Answer 37

multiple epitopes (different regions)on one or more a ntigens

Question 38

polyclonal antibodies is made from ____

Answer 38

multiple antibody-producing cells

Question 39

polyclonal antibodies = ___ regions

Answer 39

different

Question 40

If antigen contains multiple proteins, resulting polyclonal antibodies recognize ______

Answer 40

multiple antigens

Question 41

sometimes polyclonal antibodies are made to _______on a single particle (viruses)

Answer 41

multiple proteins

Question 42

monoclonal antibodies can recognize _____

Answer 42

single epitope on a single antigen

Question 43

monoclonal antibodies is made from ____

Answer 43

a single-antibody producing cell

Question 44

Monoclonal antibodies = ___ regions

Answer 44

single region (within a protein)

Question 45

monoclonal antibodies are only able to recognize _____

Answer 45

one thing

Question 46

monoclonal antibodies offer us _____

Answer 46

specificity

Question 47

production of monoclonal antibodies method? benefit?

Answer 47

1) Produce and select hybrid of myeloma (cancer)and B cell that produces desired antibody >>hybridoma 2) Screen for hybridomas that produce antibody of interest (ex. binds organelle, structure or protein of interest) 3) Each hybridoma produces one unique antibody Benefit: Do not need highly purified antigen to produce monoclonal antibodies

Question 48

monoclonal antibodies uses

Answer 48

1) infectious disease 2) diagnostic tool 3) bioengineering

Question 49

ZO1 protein at TJ is a ___

Answer 49

large peripheral membrane protein

Question 50

ZO1 protein & co-immunoprecipitation & Western Blot helps us to ____

Answer 50

identify other proteins associated with TJs

Question 51

Western blot tells you that ____

Answer 51

those two proteins interact but not where they interact

Question 52

Transmembrane proteins that are associated with TJs are ____

Answer 52

occludin or claudin

Question 53

Trans-epithelial resistance (TER)

Answer 53

the measurement of electrical resistance across a cellular monolayer

Question 54

TER is used to confirm the ____

Answer 54

the integrity and permeability of the monolayer

Question 55

Trans-epithelial flux is a measure of _____

Answer 55

transit across an epithelium

Question 56

↑ TER = ____ trans-epithelial flux

Answer 56

↓

Question 57

scrambled protein helps us to determine if protein action is ___

Answer 57

sequence -specific

Question 58

↑ trans-epithelial flux = ___ TER

Answer 58

↓

Question 59

Loss of resistance to ion current correlates with_____

Answer 59

increase in flux of small molecules

Question 60

Junction integrity can be affected by ____

Answer 60

pathogenic microbes

Question 61

______(e.g. ____) serve as entry factors for some viruses but they may not affect ____

Answer 61

Claudins CLDN1 function of TJ

Question 62

WNV (West Nile virus) infection targets a subset of ___, reducing ____ and increasing ___

Answer 62

Tight Junction proteins for degradation (claudins) TER trans-epithelial flux

Question 63

WNV-induced degradation of tight junction proteins involves ___ and requires ___

Answer 63

endocytosis dynamin