exam 2: lecture 7

Question 1

cellular junctions

Answer 1

what holds cells tgt

Question 2

what are the two major types of junctions?

Answer 2

1. adhesive junctions (adherens- hold things tgt)
2. transmitting junctions (allow things to move/ transport from one cell to another)

Question 3

Adhesive: Desmosome

Answer 3

not waterproof; has leakage
highly structured

structure:
core (desmocolins): tiny spikes between the intracellular space of 2 membranes
plague: thick flat mats (on each side of a cell)
desmogleins: nails that hold plague onto membranes
tonofilament: flagella-looking that extend into cytosol to attached to cytoskeleton)

Question 4

tight junctions

Answer 4

water proof
claudins
prevent leakage and transport solutes

Question 5

adhesive: adhesion belt

Answer 5

made up of tight junctions

epithelial cells in the small intestine

Question 6

transmitting junction: gap junctions

Answer 6

allow direct cell-to-cell transfer of ions and small molecules
connexions

Question 7

transmitting junction: plasmodesmata

Answer 7

channels between adjacent plant cells

allow ions, small molecules, water thru the cell walls
openings: desmotubule

Question 8

Adhesive: focal adhesions & hemidesmosomes

Answer 8

junctions that hold cells to substrate & help motility

Question 9

how does focal adhesions work?

Answer 9

1. hold cell down to intercellular matrix
2. amoeboid motion( to move forward)

-integrin (fibronectin receptor) is a transmembrane protein at the extracellular matrix
-bind to talin
-bind to vinculin
-next to vinculin, there are actin filaments
-to connect one complex to another: alpha-actinin

Question 10

How do hemidesmosomes work?

Answer 10

half a hemidesmosomes
bound to intermediate filaments cells in intestinal tracts (used for ones that held in place)

its plague is attached to series of proteins
-plectin