Exam 2: Chp 19

Question 1

Fibroblasts

Answer 1

main source of connective tissue extracellular matrix

Question 2

Actin linked cell matrix junction

Answer 2

anchor’s actin filaments in the cell to the extracellular matrix

Question 3

hemidesmosome

Answer 3

anchors intermediate filaments in cell to the extracellular matrix

Question 4

Adherens junction

Answer 4

connect actin filament bundles in cell to the extracellular matrix

Question 5

Desmosomes

Answer 5

connect intermediate filaments in one cell to that of the next

Question 6

Tight junctions

Answer 6

seal cells together, serving as a selectively permeable barrier

Question 7

claudin

Answer 7

binds two cells together in a tight junction

Question 8

occludin

Answer 8

binds two cells together in a tight junction

Question 9

Gap junctions

Answer 9

create channels that couple cells electrically and metabolically

Question 10

connexins

Answer 10

form connexons

Question 11

connexons

Answer 11

one connexon from one cell binds to that of the next, creating a gap junction

Question 12

homomeric connexon

Answer 12

has the same types of connexins

Question 13

heteromeric connexin

Answer 13

has different types of connexins

Question 14

homotypic connexon channel

Answer 14

same types of connexins

Question 15

heterotypic connexon channel

Answer 15

different types of connexins

Question 16

Cadherins

Answer 16

link cells at cell-cell anchoring junctions; desmosomes and adherens

Question 17

Catenin

Answer 17

attaches cadherin to actin in adherens, is unfolded with tension

Question 18

vinculin

Answer 18

recruited to catenin when it becomes unfolded

Question 19

How is cortical tension avoided in cell-cell adhesion?

Answer 19

Rac activation and Rho inhibition is triggered by cadherin clustering, allowing more adherens to form

Question 20

Plakin

Answer 20

attaches cadherin to intermediate filaments in desmosomes

Question 21

Integrins

Answer 21

anchor cells to the extracellular matrix in hemidesmosomes and actin linked matrix junctions

Question 22

Plectin

Answer 22

links intermediate filaments to integrin in hemidesmosomes

Question 23

Talin

Answer 23

links intermediate filaments to integrin in actin linked matrix junctions

Question 24

Inactive integrin

Answer 24

folded and connect bind with cytoskeletal linker proteins or extracellular matrix

Question 25

Glycosaminoglycans

Answer 25

(-) unbranched polysaccharides with repeating disaccharide units usually linked to a protein by a linkage tetrasaccharide

Question 26

Linkage tetrasaccaride

Answer 26

links glycosaminoglycans to proteins

Question 27

Gylcosaminoglycan function

Answer 27

aggregate with proteoglycans to form large polymeric complexes that hold water, form gel matrix

Question 28

Collagen

Answer 28

forms long, stiff triple apha-helical structures that organize into bundles

Question 29

collagen fibrils

Answer 29

bundles of triple alpha-helical subunits

Question 30

Collagen fibers

Answer 30

bundles of fibrils

Question 31

Fibril associated collagen

Answer 31

binds to the surface of collagen fibrils to organize them

Question 32

Elastin structure

Answer 32

hydrophobic segments cross-linked by alpha-helical segments

Question 33

Glycoproteins

Answer 33

large scaffolds with multiple binding sites for other matrix molecules

Question 34

Fibronectin

Answer 34

commonly studied glycoprotein that binds collagen, other proteoglycans, and integrins on cell surface

Question 35

Function of glycoproteins

Answer 35

organizes extracellular matrix and helps cells attach

Question 36

Basal lamina/basement membrane

Answer 36

specialized extracellular matrix beneath the epithelium

Question 37

Two major macromolecules of the basal lamina?

Answer 37

laminin and type IV collagen

Question 38

Laminin structure

Answer 38

made of 3 -polypeptide chains held together by disulfide bonds

Question 39

laminin function

Answer 39

assemble into a matrix and interact with other extracellular matrix proteins

Question 40

Type IV collagen

Answer 40

several isoforms, twist to form rope like helix