cell junctions

Question 1

what are cells held together by?

Answer 1

cell-cell adhesions, ECM or both

Question 2

what is the apical region of a cell?

Answer 2

top

Question 3

where are tight junctions found?

Answer 3

apical region

Question 4

where are adherens junctions found?

Answer 4

below tight

Question 5

where are gap junctions found?

Answer 5

towards the bottom of the cell

Question 6

what are the types of cell junctions?

Answer 6

tight
anchoring
channel forming
signal-relaying

Question 7

what do tight junctions do?

Answer 7

form a seal between cells and a fence between plasma membrane domains
allow epithelial cell sheets to serve as barriers to solute diffusion

Question 8

what are the types of anchoring junctions and what do they do?

Answer 8

adherens and desmosomes between cells
hemidesmosomes and matrix linking junction to bottom substrate

Question 9

what do anchoring junctions do?

Answer 9

respond to tension from inside and outside the tissue

Question 10

what type of junction is a gap junction?

Answer 10

channel forming

Question 11

what do channel-forming junctions do?

Answer 11

regulate metabolic and electric communication between cells

Question 12

what do gap junctions do?

Answer 12

create a passageway linking the cytoplasms of adjacent cells

Question 13

what are the types of signal relaying junctions?

Answer 13

immune and synapse

Question 14

what do signal relaying junctions do?

Answer 14

involved in communication between cells

Question 15

what links the cytoskeleton to extracellular structures or other cells?

Answer 15

TMPs

Question 16

what do cadherins do?

Answer 16

mediate the external linkage to other cells

Question 17

what do integrins do?

Answer 17

mediate the external linkage to ECM

Question 18

what is the internal linkage to the cytoskeleton by?

Answer 18

intracellular adaptor proteins

Question 19

what are cells sealed together by in tight junctions?

Answer 19

branching of TMPs called claudins and occludins

Question 20

what does mechanotransduction cause and where?

Answer 20

in adherens junctions
allows cells to respond to tension and increase their filament cross linking

Question 21

how do cell-cell junctions respond to increased tension?

Answer 21

when their actin linkages are pulled by a motor protein, it promotes additional actin recruitment, strengthening actin linkages between the junction and cytoskeleton

Question 22

what are adherens junctions made of?

Answer 22

contractile bundles of actin filaments tethered to cadherins via adaptor proteins

Question 23

what do desmosomes do in epithelial tissue?

Answer 23

give it additional tensile strength

Question 24

what do hemidesmosomes do in epithelial tissue?

Answer 24

anchor keratin filaments in an epithelial cell to the basal lamina

Question 25

what is the linkage in hemidesmosomes mediated by?

Answer 25

transmembrane attachment complex containing integrins

Question 26

what is an example of part of the body that uses gap junction signalling?

Answer 26

heart muscle cells

Question 27

how big is the pore size in gap junctions?

Answer 27

~1.4nm

Question 28

what can be transported by gap junctions and what can't?

Answer 28

can transport inorganic ions and water-soluble molecules not macromolecules or nucleic acid

Question 29

what are plasmodesmata?

Answer 29

similar to gap junctions but with larger channels and found in plants

Question 30

what do connexons do?

Answer 30

two join across intercellular gap to form an aqueous channel connecting the cytosols

Question 31

what are connexons?

Answer 31

protein assemblies

Question 32

what is the junctional complex?

Answer 32

tight, adherens and desmosomes junctions

Question 33

what do adherens junctions do?

Answer 33

connect actin filament bundles in one cell to another cell

Question 34

what do desmosomes junctions do?

Answer 34

connect intermediate filament bundles in one cell to another cell

Question 35

what do hemidesmosomes do?

Answer 35

anchor intermediate filaments in cell to ECM