L08

Question 1

what are the types of animal tissue

Answer 1

epithelial
muscular
nervous
connective

Question 2

what features do epithelial muscular and nervous tissues share

Answer 2

similar structure/make up

(high frequency of cell/cell contact

with limited cell/ECM contact)

Question 3

what are the features of connective tissue

Answer 3

lower frequency of cell/cell contact

with higher frequency of cell/ECM contact

Question 4

give examples for epithelial tissues

Answer 4

lining of gut or epidermal layer of skin

Question 5

how are epithelial cells directly connected

Answer 5

thro cell junctions

Question 6

what transmits mechanical forces from a cell to another

Answer 6

via cytoskeletal filaments

(actin/intermediate filaments)

Question 7

what is the basal lamina

Answer 7

a thin layer of connective tissue comprising mostly of ECM that epithelial cells attach to

Question 8

why are epithelial cells asymetrical/polarized

Answer 8

they have proteins at the basal end (connected to the basal lamina)

the apical end does not have these proteins

Question 9

what are the types of epithelial tissues

Answer 9

columnar

cuboidal

squamous

stratified

(check slide 16 for the pictures)

Question 10

how are epithelial cells indirectly connected

Answer 10

via ECM

Question 11

what proteins are involved in epithelial cells contacting

Answer 11

intracellular adaptor proteins

transmembrane adhesion proteins

Question 12

what are intracellular adaptor proteins attached to

Answer 12

cytoskeletal filaments

Question 13

Name three reasons why cells form tissues

Answer 13

specialization and Division of Labor

Structural Integrity and Support

Intercellular Communication and Coordination

Question 14

Name a specialized connective tissue

Answer 14

bone

Question 15

what are the types of cell junctions found in epithelial (+ muscle + nervous) tissues

Answer 15

Adherens junctions: cadherin

Desmosomes

Tight junctions

Gap junctions

Question 16

how are cadherin junctions maintained

Answer 16

via a cadherin molecule from each cell

Question 17

what are cadherin molecules attached to

Answer 17

another cadherin (extracellular)

a linker protein (intracellular)

Question 18

cadherin superfamily are Ca2+ dependent molecules

Answer 18

true

Question 19

what are the classical members of the cadherin superfamily of Ca2+ dependent molecules

Answer 19

E-cadherin, N-cadherin, P-cadherin

Question 20

cadherin binding is homophobic

Answer 20

FALSE

Question 21

cadherin binding is Ca2+ dependent

Answer 21

TRUE

Question 22

what does Ca 2+ binding do to cadherin molecules

Answer 22

Ca2+ binding prevents flexing so
promoting homophilic binding to
another cadherin

Question 23

what happens when Ca 2+ is removed

Answer 23

cells dissociate from each other

Question 24

how many extracellular domains does 1 cadherin molecule have

Answer 24

5

Question 25

what separates the extracellular domains of cadherin molecules

Answer 25

flexible hinge regions

Question 26

when are flexible hinge regions present

Answer 26

in the presence of Ca 2+

Question 27

how does the Intracellular domain of cadherins interact with actin

Answer 27

via catenins and other adapter proteins e.g. vinculin

Question 28

what are the steps of macro assembly

Answer 28

membrane protrusions initiate cell-cell contact actin and cadherin recruitment expands junction actin remodeling and myosin recruitment expands the adherens junction

Question 29

cell-cell connection leads to extending of microvilli

Answer 29

True

Question 30

what are the features of Desmosomes junctions

Answer 30

similar to adherens junctions but contain specialized cadherins that connect with intermediate filaments, also allow junctions to have strength

Question 31

what happens in tight junctions

Answer 31

epithelial tissues act as a selective permeability barrier differential transporter molecules are expressed in apical and basal plasma membranes to allow selective transport across epithelia

Question 32

give an example of a transporter molecule involved in tight junctions

Answer 32

glucose transporters in small intestine

Question 33

what are gap junctions

Answer 33

channels made from connexins and innexins

Question 34

what are the features of gap junctions

Answer 34

small; wont allow macromolecule thro Can be open or closed in response to signals (e.g. dopamine reduces gap junction communications in certain neurons in retina)

Question 35

what is the function of tight junctions

Answer 35

prevents leakage of extracellular molecules between cells help polarize the cells

Question 36

what is the function of adherens junctions

Answer 36

joins actin bundles between 2 cells

Question 37

what is the function of desmosomes

Answer 37

join intermediate filaments between cells

Question 38

what is the function of gap junctions

Answer 38

forms channels for small, water soluble molecules to pass from one cell to another

Question 39

what proteins are involved in cadherin interactions

Answer 39

p120 catenin beta catenin alpha catenin vinculin (binds alpha catenin to extend it)

Question 40

what proteins are involved in desmosomes

Answer 40

plakoglobin and plakophilin (adaptor proteins) desmoplakin (binds the intermediate filaments)

Question 41

what proteins are involved in tight junctions

Answer 41

claudin and occludin