Cell Junction and EC Matrix

Question 1

what are the 2 broad categories of animal tissues?

Answer 1

epithelial and connective tissues

Question 2

what are 4 functional classes of cell junction in animal tissue?

Answer 2

anchoring junctions
occluding junctions
channel-forming junctions
signal-relaying junctions

Question 3

what are anchoring junctions?

Answer 3

cell-cell adhesion, epithelial cells connecting
cell-matrix adhesion, cells connecting to basal lamina
bound to cytoskeletal filaments

Question 4

what are occluding junctions?

Answer 4

sealing off gaps between 2 cells
selectively permeable
also known as tight junctions

Question 5

what are channel-forming junctions?

Answer 5

passageway that links the cytoplasm of 2 cells
small molecules and ions can pass through
also known as gap junction

Question 6

what are signal-relaying junctions?

Answer 6

signal relay between cells
complex structures
does chemical and immunological synapses

Question 7

what is the name for cell-cell junctions for actin?

Answer 7

adherens junctions

Question 8

what is the name for cell-matrix junctions for actin?

Answer 8

actin-linked cell-matrix adhesion

Question 9

what is the name for cell-cell junctions in intermediate filament?

Answer 9

desmosomes

Question 10

what is the name for cell-matrix junctions in intermediate filaments?

Answer 10

hemidesmosomes

Question 11

what are tight junctions?

Answer 11

seals gap between epithelial cells (occluding junctions)

Question 12

what are cadherins?

Answer 12

cell-cell transmembrane adhesion proteins in anchoring junctions
bind to other caderins. calcium dependent

Question 13

what are integrins?

Answer 13

cell-matrix transmembrane adhesion proteins in anchoring junctions

Question 14

cadherins are made up of?

Answer 14

cadherin domains connected by calcium at hinge regions

Question 15

what is homophilic binding?

Answer 15

two of the same receptors that can bind to each other

Question 16

what is heterophilic binding?

Answer 16

receptor and ligand are 2 separate proteins

Question 17

what is affinity?

Answer 17

the absolute stickness of a binding to b

Question 18

what is avidity?

Answer 18

how many of a is on a surface

Question 19

what are adheron junctions?

Answer 19

links actin filaments

Question 20

what is an adhesion belt?

Answer 20

adheron junctions linked together

Question 21

how do you make an epithelial tube?

Answer 21

tighten adhesion belt with moving actins closer-> epithelial tube pinches off

Question 22

what is pemphigus?

Answer 22

destruction of desmosomes on epidermal cells

Question 23

the difference between tight juntions and septate junctions is that

Answer 23

tight junctions found in vertebrates and septate junctions found in invertebrates

Question 24

what are claudins and occuldins?

Answer 24

interact with each other to form a tight seal, transmembrane proteins of tight junction

Question 25

tight junctions are usually ____ to adherens and desmosome junctions

Answer 25

apical (on top)

Question 26

what are scaffolding proteins?

Answer 26

organize functional complexes, where junctions need to go on membrane

Question 27

small molecules and ions that pass through channel-forming junctions are linked _____ and _____

Answer 27

electrically and metabolically

Question 28

the channels in the channel-forming junctions are made up of ____ and _____

Answer 28

connexins and innexins. connexins in vertebrates, fruit flies and roundworms in innexins

Question 29

what are connexins?

Answer 29

4-pass transmembrane proteins

Question 30

what are connexons?

Answer 30

6 connexins together, to form channel. can be made of the same type (homotypic) or different (heteotypic) just one is called a hemichannel (needs one from each membrane to make full channel)

Question 31

why do you need gap junctions?

Answer 31

want cells to be linked (heart, few cells receive a signal to deliver to the rest)

Question 32

gap junction permeability is controlled by

Answer 32

changes in calcium and pH

Question 33

what are desmotubules?

Answer 33

link 2 plant cells, goes through cell wall

Question 34

is the extracelluar matrix diverse?

Answer 34

yes, can be bones, eyes, tendons, jelly

Question 35

what is the extracellular matrix?

Answer 35

composed of carbohydrates and proteins that form a structure that can bind cells that are embedded.

Question 36

what is the basal lamina?

Answer 36

network of extracellular matrix macromolecules

Question 37

what is the function of the basal lamina?

Answer 37

mechanical support, determination of cell polarity, cell migration, cell survival/proliferation/differentiation

Question 38

how is the basal lamina produced?

Answer 38

by cells on either side of it

Question 39

what proteins make up the basal lamina?

Answer 39

nidogen, periecan, laminin, type IV collagen, intergrin | interact with themselves or each other

Question 40

what are the fiborous proteins of the basal lamina proteins?

Answer 40

laminin, type IV collagen, nidogen

Question 41

what are the polysaccharide chains called glycosaminoglycan of the basal lamina proteins?

Answer 41

perlecan

Question 42

what protein anchors the rest in the basal lamina?

Answer 42

intergrins

Question 43

what is junctional epidermolysis bullosa?

Answer 43

mutation in a collagen in basal lamina

Question 44

what is laminin?

Answer 44

protein thats part of extracellular matrix, composed of 3 polypeptide chains twisted together

Question 45

what is anchorage dependence?

Answer 45

cells have to be attached to extracellular matrix

Question 46

what cells often escape anchorage dependence?

Answer 46

cancer cells, dont need to attach to anything

Question 47

what are integrins?

Answer 47

two chains, non-covalent association

Question 48

extracellular matrix of connective tissues is made by

Answer 48

fibroblasts

Question 49

what is glycosaminoglycan?

Answer 49

unbranched polysaccharide chain with repeating disaccharide units hydrophilic and gel-like, can withstand compressive force

Question 50

what do insects have instead of glycosaminoglycan?

Answer 50

chitin

Question 51

what do plants have instead of glycosaminoglycan?

Answer 51

cellulose

Question 52

what are the 2 subtypes of glycosaminoglycan?

Answer 52

hyaluronic acid and proteoglycans

Question 53

what is hyaluronic acid?

Answer 53

repeating disaccharides

Question 54

what is proteoglycans?

Answer 54

repeating disaccharides linked to a protein

Question 55

what is collagen?

Answer 55

fibrous protein found in all multicellular organisms, 3 chains twisted.

Question 56

describe formation of collagen

Answer 56

1. synthesis of pro-alpha chain (pro means it is grown as a longer piece so some parts will be thrown away) 2. hydroxylation of selected prolines and lysines 3. glycosylation of selected hydroxylysines 4. self-assembly of 3 pro-alpha chains 5. pro-collagen triple-helix formation 6. secretion 7. cleavage 8. assemble into fibril 9. aggregation of collagen fibrils to form a collagen fiber

Question 57

what is degradation of extracellular matrix used for?

Answer 57

tissue repair, normal turnover, cell migration, mitosis/meiosis