Lecture 8

Question 1

What are the types of cell-cell anchoring junctions

Answer 1

Adherens junctions, desmosomes

Question 2

What are the types of cell to ECM junctions

Answer 2

Focal adhesions, hemidesmosomes

Question 3

What are the types of trafficking junctions

Answer 3

Tight junctions, gap junctions

Question 4

What are the types of structural proteins

Answer 4

Collagen, elastin

Question 5

What are the types of adhesive proteins

Answer 5

Fibronectin, laminin

Question 6

Adherens junctions function, transmembrane protein component, filament component

Answer 6

Function: link adjacent cells
Transmembrane protein component: Classical cadherins
Filament component: Actin cytoskeleton (actin-belt)

Question 7

Desmosomes function, transmembrane protein component, filament component

Answer 7

Function: Intercellular adhesion
Transmembrane protein component: Desmosomal cadherins (desmoglein and desmocollin)
Filament component: Intermediate filaments

Question 8

Desmosomes and their strong interactions with __________ allows the tissues to withstand _________ forces

Answer 8

Intermediate filaments, tearing/shearing

Question 9

Membrane function/ protein components of focal adhesions

Answer 9

Function: Attaches migrating cells to the extracellular matrix
Protein components: integrin dimers link the actin cytoskeleton to proteins within the ECM
(fibronectin or collagen)
Filament components: Actin filaments

Question 10

Filament component/ function/ protein components of hemidesmosomes

Answer 10

Filament component: Intermediate filaments (cytosolic side); laminin (ECM side)
Function: Anchor epithelial cells to the basal lamina
Protein components: Integrins

Question 11

Tight junctions function, transmembrane protein component

Answer 11

Function: Form a tight seal that inhibits paracellular transport/prevent mixing of apical and basolateral membrane proteins
Transmembrane component: Claudins, Occludin

Question 12

Fibrillar collagen provides

Answer 12

Mechanical strength

Question 13

Collagen can be found where

Answer 13

Type IV collagen is a major component of basal lamina.

Question 14

Hydrophobic/ hydrophilic elastin is involved in what

Answer 14

Hydrophobic domains play an important role in elasticity. Lys in hydrophilic domains are involved in cross-linking of elastin

Question 15

A proteoglycan is composed of

Answer 15

Glycosaminoglycans which are covalently bound to a core protein

Question 16

GAGs are composed of

Answer 16

Unbranched chain of repeating disaccharides

Question 17

GAGs contain what

Answer 17

Acidic/ sulfated sugars which make them a negative charge

Question 18

Fibronectin does what

Answer 18

Links the molecules in ECM (collagen, proteoglycan), Plays a role in cell migration through ECM

Question 19

Laminin functions

Answer 19

Another major component of basal lamina

Question 20

Pemphigus cause/ function affected/ characteristic features

Answer 20

-Autoantibodies against the desmoglein
-Disruption of desmosomes (i.e., adjacent epithelial cells are loosely connected/separated easily)/Blisters, raw & crusted wounds

Question 21

Osteogenesis imperfecta cause/ function affected/ characteristic features

Answer 21

-Inherited mutations in type I
collagen (~90% cases)
-Decreased production of collagen or
production of abnormal collagen/Fracture
after minimal trauma, bone deformation

Question 22

Ehlers-Danlos syndrome cause/ function affected/ characteristic features

Answer 22

-Defective collagen synthesis
(due to inherited mutations in
collagen or collagen processing enzymes)
-Stretchy skin, hypermobile joints, easy
bruising (symptoms vary)

Question 23

Scurvy cause/ function affected/ characteristic features

Answer 23

-Prolonged vitamin C deficiency
-Impaired hydroxylation of proline and lysine in
collagen (Prolyl hydroxylase and lysyl
hydroxylase require vitamin C for their
activity)

Question 24

What is the proteoglycan core composed of

Answer 24

Core protein+ GAG’s+ PGs linked to hyaluronic acid via linker protein

Question 25

What are the 8 steps of collagen synthesis

Answer 25