Tissue Architecture

Question 1

what are intermediate filaments resistant to?

Answer 1

stretching forces

Question 2

what are the cytoskeleton filaments

Answer 2

• Intermediate filaments
• Microtubules
• Microfilaments

Question 3

intermediate filaments

Answer 3

• Great tensile strength
• Found in cytoplasm of most animal cells
• Often anchored to plasma membrane at cell-
cell junctions

• Form mesh-like structure called nuclear
lamina

Question 4

what is mutated in progeria

Answer 4

nucelar lamina

Question 5

microtubles

Answer 5

• Crucial organization role in all
eukaryotic cells
• Long and stiff hollow tubes
• Rapid assembly and disassembly
• Extend from centrosome to cell
periphery
• Form mitotic spindle for
chromosome segregation
• Part of cilia and flagella

Question 6

Role of γ−tubulin

Answer 6

nucleation of microtubules at - end

- anchor point for microtubules to grow from

Question 7

taxol

Answer 7

binds and stabilizes microtubules

Question 8

colchicine, colcemid

Answer 8

binds tubulin dimers and prevents their polymerization

Question 9

vinblastine, vincristine

Answer 9

• binds tubulin dimers and prevents their polymerization

Question 10

microfilaments

Answer 10

-Actin filaments (F-actin)
– Twisted polymer of G-actin
(globular)
– Structural polarity
• Present in all cell types
• Many are unstable
• Essential for cell movements

Question 11

phalloidin

Answer 11

binds and stabilizes actin filaments

Question 12

cytochalasin

Answer 12

-caps filament + ends preventing polymerization there

Question 13

latrunculin

Answer 13

binds actin monomers and prevents polymerization

Question 14

Extracellular Matrix and Basal Lamina

Answer 14

Components produced intracellularly and secreted
and aggregate
-Matrix which interacts with cells/tissues via
transmembrane proteins
-Composition and properties controlled and vary by
tissue type, location etc.

Question 15

types of ECM proteins

Answer 15

• proteoglycans
• collagens
• multi-adhesive matrix proteins

Question 16

ECM functions

Answer 16

• forming tissue boundaries
• determining biochem properties of EC environment
• controlling cell polarity, survival etc
• acts as reservoir for GF and binding of GF to receptor
• serve as ligand for signaling receptors

Question 17

what is the Main structural protein in
ECM/connective tissue and basal
laminae

Answer 17

collagen

Question 18

scurvy results from loss of what cofactor

Answer 18

ascorbate or iron

Question 19

what makes up basement membrane

Answer 19

1) type IV collagen
2) laminin
3) fibronectin

Question 20

ehlers-Danlos syndrome

Answer 20

-mutation in collegen or collegen synthesis genes
• Mutations alter the structure, production, or
processing of collagen or proteins that
interact with collagen
• Weakens connective tissue in the skin, bones,
blood vessels, and organs

Question 21

cell junctions

Answer 21

link cells to

neighboring cells,

Question 22

focal contacts

Answer 22

link cells to

extracellular matrix, or basil lamina

Question 23

types of cell junctions

Answer 23

1) anchoring
2) occluding
3) channel forming
4) signal relaying

Question 24

adherin junction

Answer 24

type of anchoring junction

• cadherin (ca2+ dependent)
• catenin binds to actin
• role in metastasis (loss of E cadherin)

Question 25

desmosomes

Answer 25

- type of anchoring junction - cell to cell - strength - bind to intermediate filaments

Question 26

hemidesmosomes

Answer 26

type of anchoring junction - cell to ECM via basement membrane - integrins bind to intermediate filaments

Question 27

focal adhesions

Answer 27

type of anchoring junction - cell to matrix - integrins bind to actin - imp in resisting sheer stree

Question 28

tight junctions

Answer 28

- occludin and claudin bind to actin | - maintains conc gradient (keeps cell closed off)

Question 29

gap junctions

Answer 29

- connexins bind to adaptors in other junctions | - small molecule transport between cells

Question 30

major domains of CAMS

Answer 30

``` – Extracellular (binding to adjacent cell/matrix proteins – Transmembrane (links CAM to membrane) – Cytoplasmic (bind to cytoskeleton via linker proteins) ```

Question 31

what are 4 major families of CAMs

Answer 31

1) cadherins 2) Ig superfamily 3) integrins 4) slectins

Question 32

cadherin superfamily

Answer 32

-Ca2+ dependent adhesion molecule – Important in formation of junctions between cells (epithelial “sheets”)

Question 33

classic cadherins

Answer 33

- interact with catenin - associated with adherin junction - linked to actin cytoskeleton

Question 34

atypical cadherins

Answer 34

no interaction with catenin or link to actin cytoskeleton

Question 35

what can serve as biomarkers for metastic tumors

Answer 35

cadherins | -epithelia to mesenchymal transition

Question 36

Ig superfamily CAMS

Answer 36

Family of more than 25 Calcium-independent transmembrane glycoproteins • Immune cell interactions -– Contain a variable number of immunoglobulin-like domains – Expressed on vascular endothelial cells and bind to various integrin molecules – Involved in recognition, binding, or adhesion processes of cells – Homophilic and heterophilc binding

Question 37

selectins

Answer 37

Family of calcium dependent glycoproteins – Bind to extracellular carbohydrates – Play important roles in host defense mechanism Increased presentation during local inflammatory response • WBC surface makers include carbohydrates which act as ligands for selectins • Low-affinity of selectins to ligands allows for leukocyte “rolling” during leukocyte adhesion cascade

Question 38

what type of selectins are there

Answer 38

Include: • Endothelial (E)-selectin • Leukocyte (L)-selectin • Platelet (P)-selectin

Question 39

integrins

Answer 39

Couple the extracellular matrix to cell cytoskeleton -can activate signaling pathways - cell - cell interaction via beta2 family -Integrins on leukocytes allow for adhesion and transmigration to sites of infection