Tissue Architechture

Question 1

What are the four main functions of the cytoskeleton?

Answer 1

They are:

1. Dynamic
2. Adaptable
3. Stable
4. Strong

Question 2

What are the three types of cytoskeletal filaments?

Answer 2

1. intermediate filaments
2. microtubules
3. microfilaments

Question 3

What do intermediate filaments do and what is an example?

Answer 3

They have great tensile strength (rope like), bear mechanical stress, cell to cell communication, form nuclear lamina

Question 4

What are examples of different types of intermediate filaments?

Answer 4

keratin in epithelial
vimentin in connective tissues
neurofilaments in nerve cells
nuclear lamins

Question 5

What happens if someone has a mutation in their nuclear lamina?

Answer 5

Leads to progeria = accelerated aging

Question 6

What are the key roles of microtubules?

Answer 6

used in mitotic spindle
cilia/flagella movement
organization*

Question 7

How are microtubules made?

Answer 7

Minus end and plus end, minus end have y-tubulin that anchor at base and then alpha-beta tubulin get added towards the plus end

Question 8

What does the microtubule specific durg Taxol do?

Answer 8

binds and stabilizes microtubules, preventing growth of cell so cells dont divide

Question 9

What are the key roles of microfilaments?

Answer 9

make actin filaments (F-actin, polymer of Gactin), important for polarity and movement

Question 10

What does the actin specific drug Phalloidin do?

Answer 10

binds and stabilizes filaments whic makes the visualization of actin cytoskeleton easy

Question 11

What are the results of the different types of proteins that bind to and modify actin properties?

Answer 11

Stabilization
Strengthen
Cross-linking
Oragnization

Question 12

What do proteoglycans do?

Answer 12

part of the extracellular matrix, allows cell to cell interactions

Question 13

What are the types of collagen?

Answer 13

sheet forming (type IV)
Fibrillar collagens (types 1,2,3,5) forms triple helix, located at the basement membrane

Question 14

What do laminin and fibronectin do?

Answer 14

multi-adhesive matrix proteins : they are found at the basement membrane with collagen

Question 15

What are the ECM functions (6)?

Answer 15

1. Anchoring
2. Biomechanical
3. Polarity
4. Migration
5. Growth Factors
6. Proteolytic Clevage

Question 16

Why is collagen important to the ECM?

Answer 16

Main structual protein in ECM/connective tissue and basal laminae

Question 17

When collagen is produced, is it active? When does it become active?

Answer 17

It is not active inside the cell where it is made. When collagen is secreted out of cell as procollagen, it is then cleaved and activated to collagen (homo or heterodimer Triple helix formed)

Question 18

What is need so scurvy does not occur?

Answer 18

Prolyl hydroxylase or lysl hydroxylase (wont form collagen correctly) which requires Fe and ascorbate as co factors

Question 19

What causes Ehlers-Danlos?

Answer 19

A mutation in collagen’s fibrous protein or enzymes that results in extremely stechy skin :)

Question 20

What do anchoring junctions do and what CAMs are anchoring?

Answer 20

Anchor cells to neighboring cells and membrane basement.

Cadherins, Desmosomal cadherins, integrins

Question 21

What do occluding junctions do?

Answer 21

also known as tight junction, control solute flow (occludin claudin)

Question 22

What do signal-relaying junctions do?

Answer 22

communicate by sending small molecules across (neuronal) (connexins)

Question 23

What do channel forming junctions do?

Answer 23

create channel between cells

Question 24

What are the three major domains of cell adhesion molecules (CAMs)?

Answer 24

Extracellular
Transmembrane
Cytoplasmic

Question 25

What are characteristics of cadherins (adheren junctions)?

Answer 25

They are all Ca2+ dependent adhesion moledcules, important in forming junctions between cells. make homophilic interactions

Question 26

What are the types of different cadherens?(4)

Answer 26

E-cadherin (epithelial)
N-cadherin (neural)
VE-cadherin (vascular-endothelial)
LI-cadherin (liver-intestine) (ATYPICAL)

Question 27

What does EMT stand for and what cadherins will tell you how invasive a cancer is?

Answer 27

EMT is epithelia to mesenchymal transition (for metastatic tumors. In less invasive bladder cancer, E-cadherin will be shown, in more invasive N cadherin will be shown

Question 28

What is the role of Ig superfamily CAMs?

Answer 28

they interact with immune cells (Ca independent)

Question 29

Waht kind of binding are Ig CAMs capable of ?

Answer 29

Heterophilic and homophilic binding

Question 30

What two roles do selectins perform in immune repsonse?

Answer 30

Assist in rolling adhesion (low affinity slowing of leukocytes (WBC)) and binding of extracellular carbohydrates

Question 31

What are selectins dependent on?

Answer 31

Calcium dependent (glycoproteins!)

Question 32

What increases the presence of selectins?

Answer 32

infalmmation

Question 33

What role do integrins play in rolling adehsion?

Answer 33

They are the high affinity stops after selectins slow the leukocyte down. Using beta2 family of integrins

Question 34

What other two functions do integrins perform?

Answer 34

they couple extracellular matrix to the cytoskeleton using fibronectin, collagen, and laminin.

They activate signaling pathways through RTK

Question 35

What proteins are needed for cell-matrix ?

Answer 35

Integrins

Question 36

What proteins are needed for cell-cell junctions?

Answer 36

Cadherins/desmosomal cadherins, occludins, connexins