Cell Junctions and Surface Specializations Flashcards Preview

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Flashcards in Cell Junctions and Surface Specializations Deck (44):
1

Two classes of cell adhesion molecules

Calcium dependent; calcium independent

2

Calcium dependent adhesion molecules

Cadherins, selectins

3

Calcium independent adhesion molecules

integrins, immunoglobulin superfamily

4

Function of cadherins

Maintain cell-cell contacts. Primarily homophilic adhesions (binds to other cadherins)

5

How does calcium removal affect cadherins?

Calcium removal stops adhesion and makes cadherins vulnerable to proteases

6

Adhesion using cadherins is stabilized by

actin cytoskeleton (binding to actin via catenins)

7

What is the loss of E-cadh erin associated with?

Tumor metastasis

8

E-cadherin is found in

epithelia

9

N-cadherin is found in

neural cells

10

Selectins

Bind to carbohydrates-each selection has carbohydrate recognition domain (CRD). Important for controlling movement of leukocytes from blood into tissues.

11

P-selectin

platelets, activated endothelial cells

12

E-selectin

activated endothelial cells

13

L-selectin

leukocytes (homing receptor)

14

In selectins, calcium bound at the sides of the CRD regulates

the conformation of the domain and its ability to bind carbohydrates

15

Outside the cell, the binding site on integrin is on what subunit?

β subunit (binds laminin, fibronectin, tenascin, vitronectin, collagen...)

16

Inside cell (Integrin) binds to cytoskeletal actin

via actin binding proteins (talin, vinculin, α-actinin)

17

Adhesion of integrins is stabilized (and destabilized) by

actin cytoskeleton

18

Immunoglobulin Superfamily

share Ig-like domain;

19

HIV-1 receptor(CD4 on lymphocyte) is a member of what family

Immunoglobulin Superfamily

20

Occluding (tight) junctions

prevent free passage across an epithelial layer

21

In occluding junctions, transmembrane occludin interacts with...

claudin

22

Why are tight (occluding) junctions medically important ?

Tight junctions are medically important because it can prevent the delivery of drugs to the bloodstream or tissues

23

Tight junctions determine

epithelial polarity

24

Cell junction which has a "belt-like distribution"

Zonula Adherens

25

Zonula Adherens involves interaction primarily with

cadherins and catenins

26

Desmosomes are stabilized by

intermediate filaments(keratin or vimentin)

27

Desmosomes lack

afadin-nectin and catenin complexes

28

Intercellular "rivets"-spot like junction

desmosomes

29

Hemidesmosomes

anchor basal portion of cell to basal lamina

30

What is the only asymmetrical junction

Hemidesmosomes

31

Anchoring filaments involved in Hemidesmosomes

Laminin 5

32

Communicating junction between cells

Gap junctions

33

Six integral membrane proteins called connexins associate to form a

connexon

34

Gap junctions link cells ________ and _________

chemically and electrically

35

Connexin 26 mutation

deafness

36

Connexin 32 mutation

Charcot-Marie-Tooth neuropathies: progressive peripheral nerve degeneration

37

Connexin 50 mutation

congenital cataracts and blindness

38

Microvilli increase _____ ____ for _________

surface area; absorption

39

Structure of cilia and flagella

9+2 array of highly stable microtubules

40

Cilia

hairlike appendages that move fluid-develop from basal bodies (derived from centrioles)

41

Flagella

propeller for sperm motility (Dyneins provide force for movement)

42

Kartagener's syndrome

Loss of dynein = ciliary dyskinesia. Poor respiratory clearance and reproductive sterility

43

long branching projections that have an actin core(no microtubules or basal body)

non-motile stereocilia

44

What has the same substructure of microvilli?

Stereocillia