Cell junctions

Question 1

what are the three types of interactions between cell junctions

Answer 1

occluding junctions
anchoring junctions
communicating junctions

Question 2

what is the main function of occluding junctions

Answer 2

seal cells of a epithelium, preventing small molecules leaking from one side to the other

Question 3

what are the two types of occluding junctions

Answer 3

tight and septate (in insects)

Question 4

what does formation of occluded junctions lead to

Answer 4

provides selectively permeable membranes

Question 5

what two sides do polarised cells have

Answer 5

apical and basal

Question 6

describe transport proteins in relation to occluding junctions

Answer 6

different transport protiens at different locations

Question 7

describe the seal of occluded junctions

Answer 7

not absolute, controllable (important for aa and small sugars)

Question 8

what is a component of epithelial cells

Answer 8

epi villi

Question 9

what are epi-villi

Answer 9

they increase surface area

Question 10

what is the function of epithelial cells

Answer 10

specialised proteins that pump molecules across membranes - up conc gradient

Question 11

describe the composition of tight junctions

Answer 11

row of opposing transmembrane echesion proteins

Question 12

name two transmembrane adhesion proteins

Answer 12

claudins and occodin

Question 13

what are anchoring junctions

Answer 13

mechanically attach cells to other cells or to the matrix

Question 14

describe the two actin filament attacthcment sites

Answer 14

cell-cell junctions (demosomes)

cell-matrix junctions (hemidesmosomes)

Question 15

where are anchoring junctions found

Answer 15

in tissues that have mechanical stress- heart, muscle, epidermis etc

Question 16

what do desmosomes do

Answer 16

adhere junctions

hold cells together using transmembran eproteins and cadherins

Question 17

what do hemidesmosomes do

Answer 17

focal ahesions

bind to extracellular matrix using transmembrane proteins, integrins

Question 18

describe a commonality between desmosomes and hemidesomosomes

Answer 18

both have intracellular anchoring proteins that connect junction to cytoskeleton

Question 19

what are two examples of adheres junctions of cell-cell actin filaments

Answer 19

various forms but adhesion belts in epithelial cells

Question 20

where is the location of adheres junctions cell-cell actin filaments

Answer 20

below the tight junctions encircling the cell and form before tight junctions