Cell-Cell Adhesion and ECM

Question 1

Adherens junctions

Answer 1

Connects actin filament bundle in one cell with that of the next

Question 2

Desmosomes

Answer 2

Connects intermediate filaments in one cell to those of the next cell

Question 3

Tight junctions

Answer 3

Seals gaps between epithelial cells

Question 4

Gap junctions

Answer 4

Allows passage of small water-soluble molecules from cell to cell

Question 5

(T/F) Given the numerous processes inside cells that are regulated by changes in Ca2+ concentration, it seems likely that Ca2+ dependent cell-cell adhesion are also regulated by concentration

Answer 5

F; They are mediated by the concentration, but they can’t be regulated because cells cannot control the Ca2+ concentration outside of itself.

Question 6

(T/F) Tight junctions perform two distinct functions; they seal the space between cells to restrict paraceullar flow, and they fence off plasma membrane domains to prevent the mixing of apical and basolateral membrane proteins.

Answer 6

T

Question 7

(T/F) The elasticity of elastin derives from its high concentration of alpha helices, which act as molecular springs

Answer 7

F; The lack of alpha helical structure is actually what makes it elastic, since the hydrogen bonds aren’t there to keep it rigid

Question 8

(T/F) Integrins can convert mechanical signals into intraceullar molecular signals

Answer 8

T

Question 9

The function of adheren junctions are to

Answer 9

Sense forces and modify local actin structure accordinly

Question 10

The function of desmosomes are to

Answer 10

Interacts with keratin in epithealial cells and desmin filaments in heart and muscle cells to resist mechanical stress

Question 11

The function of tight junctions are to

Answer 11

Seal gaps between epitheial cells to make sure nothing escapes, as well as form fences to prevent drifting of apical cell membrane proteins.

Question 12

The function of gap junctions are to

Answer 12

Allow passage of water soluble molecules between cells and create channels that can be opened and closed by voltage and neurotransmitters.

Question 13

The structure of collagen

Answer 13

Trimer of glycoproteins

Question 14

The structure of proteoglycans

Answer 14

GAG’s form chains linked to a core protein

Question 15

The structure of fibronectin

Answer 15

Repeated proteins linked together with different binding domains

Question 16

The structure of lamina

Answer 16

Trimer of proteins that interact with collagen and forms lattice structures

Question 17

The function of collagen

Answer 17

Give strength and resist mechanical tension

Question 18

The function of proteoglycans

Answer 18

Attracts water creating a gel-like barrier that serves to resist mechanical compression

Question 19

The function of fibronectin

Answer 19

Creates a large number of binding sites that span the entire cell to promote fibril formation.

Question 20

The function of lamina is

Answer 20

To cradle cells and keep everything in place