surface specializations and cell junction

Question 1

where can the junctional complexes be seen on a slide?

Answer 1

terminal bar

Question 2

forms bands around the entire apical circumference of cell walls

Answer 2

zonula occludens

Question 3

What are the proteins found in zonula occludens?

Answer 3

integral membrane: claudins & occludin
peripheral membrane: ZO 1,2,3; cingulin; spectrin
cytoskeletal: actin

Question 4

how do zonula occludens influence cell polarity?

Answer 4

-restrict movement within cell membrane
-separate apical and basolateral domains
-can seal intercellular space

Question 5

how do zonula occludens serve as a selective permeability barrier?

Answer 5

-regulate paracellular transport/passive diffusion
-facilitate/promote transcellular transport (ion transporter)

Question 6

how do zonula occludens serve in innate immune/host defense function?

Answer 6

bacteria in intestinal lumen leads to large fluid release via open paracellular pathway to flush surface

Question 7

-important belt like cell-cell adhesion units
-thought to mediate folding and other 3D shapes of epithelia via actin and myosin interactions
-required for tight junction formation

Answer 7

zonula adherens

Question 8

what are the proteins found in zonula adherens?

Answer 8

transmembrane: Cadherins
peripheral membrane: Catenins, a-actinin, vinculin
cytoskeleton: actin

Question 9

terminal web

Answer 9

-comprised primarily of actin microfilaments
-anchored to the zonula adherens
-stabilizes the apex of the cell

Question 10

-spot-like cell-cell adhesion units
-serve as membrane anchor for the cytoskeleton
-transmit tensile strength through epithelium
-cell signaling

Answer 10

macula adherens (desmosomes)

Question 11

what are the proteins found in macula adherens?

Answer 11

transmembrane: desmocollins & desmogleins
peripheral membrane: desmoplakin, plakoglobin, plakophilin
cytoskeletal: keratin

Question 12

describe the positioning of desmosomes:

Answer 12

-part of junctional complex, but not constrained to this position
-found along all lateral walls

Question 13

tetraspans

Answer 13

connexins

Question 14

hexameric hemichannels

Answer 14

connexons

Question 15

what is a gap junction made of

Answer 15

connexon of 1 cell docks with connexon of adjacent cell

Question 16

-spot-like cell-cell communication & resource-sharing units
-intracellular channel function
-action potential transmission
-metabolite/nutrient diffusion
-second messenger diffusion
-induction/modulation of cell processes

Answer 16

gap junctions

Question 17

what systems are typically affected with defects in gap junctions?

Answer 17

sight, hearing, heart, skin

Question 18

what is the microscopy difference between basement membrane and basal lamina?

Answer 18

basement membrane- light microscopy (special stains)
basal lamina- electron microscope

Question 19

what are the 2 layers of the basement membrane?

Answer 19

basal lamina and reticular lamina

Question 20

what are the principal functions of the basement membrane?

Answer 20

-selective permeability
-physical support; transmit forces to adjacent connective tissue
-instructive role/signaling function; critical for positioning of brain cells

Question 21

what are the principal components of the basal lamina?

Answer 21

-lamina rara (laminin, nidogen, XVII collagen BPAG2)
-lamina densa (IV collagen, perlecan)

Question 22

what are the principal components of the reticular lamina?

Answer 22

-reticular fibers (mainly collagen III)
-VII collagen
-fibronectin

Question 23

how do type IV and type III collagen produce a layer that is difficult for microorganisms and metastasizing cells to pass through?

Answer 23

type iv produces and fine feltwork and type III produces a larger grain network

Question 24

a short collagen that anchors the lamina densa to the reticular lamina

Answer 24

Type VII

Question 25

anchors the lamina densa to type III collagen fibers in the reticular layer

Answer 25

type VII collagen fibers

Question 26

-spot-like cell-matrix adhesion units -anchor cells to the basal lamina -transmit tensile strength from epithelium to ECM

Answer 26

hemidesmosomes

Question 27

what are the proteins found in hemidesmosomes?

Answer 27

integral: integrins, XVII collagen (BPAG2) peripheral: plectin, BP180 cytoskeleton: keratin

Question 28

what causes skin blistering?

Answer 28

autoantibodies generated against desmoglein1 & 3 attack proteins in macula adherens

Question 29

Keratin intermediate filaments bind _______, _______ in attachment plaque.

Answer 29

plectin, BP180

Question 30

Integrins attached to plectins bind to ____________ in the lamina rara.

Answer 30

laminins

Question 31

Integrins and laminins then connect to the __________ in the lamina densa

Answer 31

type IV collagen

Question 32

The lamina densa is tied to ___________ in the reticular lamina by fibronectin and type VII collagen.

Answer 32

type III collagen

Question 33

desmosome vs hemidesmosome proteins?

Answer 33

-plaque: desmoplakin vs plectin -transmembrane: cadherins vs integrins

Question 35

-spot-like cell-matrix adhesion unit that anchors cytoskeleton to ECM -detects and transduces extracellular signals

Answer 35

focal adhesions

Question 36

-colocalizes with integrin -mediates adhesion, growth, survival, proliferation, migration, invasion -overexpressed in numerous cancer types and proposed target for anti-cancer therapy

Answer 36

focal adhesion kinase

Question 37

what are the proteins found on focal adhesions?

Answer 37

-integral: integrins -peripheral: vinculin, talin, a-actinin, paxillin -cytoskeletal: actin

Question 38

what is the purpose of basolateral membrane infoldings and outfoldings?

Answer 38

-increase cell surface area -common in cells that transport fluids and electrolyte

Question 39

-carbohydrate-rich coat; well-developed on absorptive epithelial -contributes to cell-cell recognition, communication, and intracellular adhesion

Answer 39

glycocalyx

Question 40

-contain actin core anchored to terminal web -increase surface area for absorption -not motile -visible glyocalyx

Answer 40

microvilli

Question 41

What proteins stabilize the actin core and attach it to the microvillar membrane?

Answer 41

villin, fimbrin, and mysoin 1

Question 42

-very tall microvilli -contain actin cores -commonly seen where fast absorption is necessary -apical specializations on hair cells of the inner ear

Answer 42

stereocilia

Question 43

contains axoneme microtubule doublet core anchored into a basal body

Answer 43

cilia

Question 44

cytoskeleton of 9 figure 8 shaped doublets and a central pair of microtubules

Answer 44

axoneme

Question 45

like a centriole, has 9 triplet microtubules and lacks central pair

Answer 45

basal body

Question 46

movement of dynein arms via ATP hydrolysis (allow cilia to move luminal contents)

Answer 46

effective stroke

Question 47

passive elastic connections from the radial spokes (allow cilia to move luminal contents)

Answer 47

recovery stroke

Question 48

what issues are caused by diseases that affect axoneme motility?

Answer 48

respiratory symptoms and male sterility

Question 49

-derive from an axoneme (no central pair) from a centriole -most lack dynein so they are non-motile (except ventral node) -detect physical and chemical changes in the extracellular environment

Answer 49

primary cilia

Question 50

what happens when primary cilia of the kidney are defected?

Answer 50

polycistic kidneys

Question 51

defects in beating of nodal cilia result in 50/50 chance of ____________

Answer 51

situs invertus

Question 52

how can cilia defects affect the epidermis

Answer 52

can cause some forms of skin cancer