Cell Adhesion

Question 1

How are mechanical stresses transmitted from cell to cell?

Answer 1

By cytoskeletal filaments anchored to cell-matrix and cell-cell adhesion sites.

Question 2

What does the extracellular matrix bear?

Answer 2

Mechanical stresses of tension and compression

Question 3

Epithelial tissues

Answer 3

Cells are directly connected with a minimal extracellular matrix
Epithelial tissue can include basal lamina

Question 4

Connective tissues

Answer 4

Cells dispersed through extracellular matrix

Question 5

The function of epithelial cells

Answer 5

Lines surfaces, cavities, and organs
eg. skin, digestive tract

Question 6

Are epithelial cells polarized

Answer 6

yes

Question 7

order of junctional complexes in epithelial cells (mature)

Answer 7

tight junctions, adherens junctions desmosomes, gap junctions

actin linked and hemidesmosome (in basal region)

Question 8

tight junctions

Answer 8

seals the gap between epithelial cells
form sealing strands

Question 9

cell-cell anchoring junctions

Answer 9

adherens junctions and desmosomes

Question 10

adherens junctions

Answer 10

connects actin filament bundle in one cell with that in the next cell
form adhesion belts. actin filaments don’t go through to other side.

Question 11

desmosome

Answer 11

connects intermediate filaments in one cell to those in the next cell

Question 12

channel forming junction

Answer 12

gap junction

Question 13

gap junction

Answer 13

allows the passage of small water-soluble molecules from cell to cell

Question 13

cell-matrix anchoring junctions

Answer 13

actin-linked cell-matrix junction and hemidesmosome

Question 13

actin-linked cell-matrix junction

Answer 13

anchors actin filaments in cell to extracellular matrix

Question 14

hemidesmosome

Answer 14

anchors intermediate filaments in cells to extracellular matrix

Question 15

how are cell-cell junctions mediated?

Answer 15

cadherins

Question 16

how are cell-extracellular matrix junctions mediated?

Answer 16

integrins

Question 17

What can the cytoskeleton be

Answer 17

actin or intermediate filaments

Question 18

cadherins

Answer 18

adherens junctions
they are transmembrane proteins expressed by both cells

Question 18

Cadherin interactions

Answer 18

Cadherins interact homophilic interactions of their extracellular domains
These interactions require Ca2+

Question 19

How do cells sort into groups based on homophilic cadherin interactions?

Answer 19

Homophilic interactions from between cells expressing E-cadherins
* Homophilic interactions from between cells expressing N-cadherins
* No heterophilic interactions occur between E-cadherins & N-cadherins
* Result: cells expressing different
cadherins sort into two separate
groups that do not interact

Question 20

What do cadherins indirectly interact with?

Answer 20

actin
These interactions indirectly link the
actin cytoskeleton between adjacent
cells in epithelial tissues

Question 21

what can adhesion belts mediate

Answer 21

morphogenesis

Question 22

Neural tube closure

Answer 22

Adhesion belt contraction pulls cells to form a tube Cells express different cadherins to establish new interactions and ensure neural tube closure

Question 23

How do tight junctions define domains of the cell?

Answer 23

Apical domain faces the surface, cavity, or organ * Domains are defined and maintained by tight junctions * Basal domain faces the inside of the body * Basal & lateral domains often grouped into the basolateral domain

Question 24

What forms tight junctions

Answer 24

claudins and occludins

Question 25

what type of interactions do claudins and occludins have

Answer 25

homophilic interactions with their extracellular domains to directly link adjacent cells * Many rows of these proteins form a functional tight junction

Question 26

Why do tight junctions help

Answer 26

they limit diffusion in the extracellular space prevent membrane proteins from moving between the apical and basolateral domains

Question 27

Tight junctions regulate what enters and organism

Answer 27

Tight junctions stop anything from directly diffusing from the gut lumen into connective tissue & blood Active transporters must move glucose into the epithelial cell on the apical domain Passive carriers in the basolateral domain allow glucose to diffuse out of the epithelial cell into the connective tissue/blood Tight junctions keep the correct transporters in their correct domains of the cell

Question 28

what mediates cell to cell matrix junctions

Answer 28

integrin heterodimers

Question 29

how do Integrins anchor actin filaments to the extracellular matrix

Answer 29

Integrin heterodimers directly bind extracellular matrix proteins Integrins have a transmembrane domain Integrins indirectly interact with actin filaments Actin-integrin-extracellular matrix interactions can provide the adhesion necessary for cell migration

Question 30

how do polarity cues establish cell cohesion

Answer 30

Adherens junctions form first * Adherens junctions provide polarity cues to define apical from basolateral domains * Tight junctions form apical to the adherens junctions