Cell Junctions

Question 1

Freeze fracture

Answer 1

Method for preparing tissues for electron microscopy is used to characterize cell junctions

E face - exoplasmic
P face - protoplasmic

Question 2

3 functional classes of cell junctions

Answer 2

1. Occluding junctions (Tight)
2. Anchoring junctions (Desomsomes, hemidesmosomes)
3. Communicating junctions (Gap)

Question 3

Tight junction

Answer 3

occluding junction that forms tight seal that inhibits passage of molecules and serves as molecular fence to prevent membrane proteins from diffusing between basal and apical sides, binds to F-actin

Question 4

Sealing strands

Answer 4

occludins and claudins make tight junctions and bind to anchoring proteins and actin

Question 5

Anchoring junctions

Answer 5

link cytoskeleton to adjacent cells or ECM through actin filaments and IF, desmosome (connects two cells), hemidesmosome (connects cell to ECM)

Question 6

Anchoring junctions that connect to actin filiaments

Answer 6

Adherens junction (cell-to-cell)
Focal adhesion (cell-to-ECM)

Question 7

Anchoring junctions that connect to intermediate filiaments

Answer 7

Desmosomes (cell-to-cell)

Hemidesmosomes (cell-to-ECM)

Question 8

Gap junction

Answer 8

communication junction composed of multiple connexon subunits, hollow in the middle

Question 9

T or F: Cadherins of tight junctions can be linked to signaling molecules

Answer 9

True

Question 10

Adhesion can activate intracellular ‘promiscuous’ signaling pathway

Answer 10

Can activate pathway without specific ligand binding