Lecture 11: Tissue Architecture Flashcards Preview

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1

What is more stable - a single protofilament or multiple protofilaments?

Multiple Protofilaments

-single ones are thermally unstable

2

Why might intermediate cytoskeletal filaments be resistant to stretching forces?

Lateral contacts dominate in the organization of fibers, preventing stretching

-Rope like properties

3

What are the three types of Cytoskeletal Filaments?

1. Intermediate Filaments

2. Microtubules

3. Microfilaments

4

For intermediate filaments:

What do they do?

Where are they found?

Where are they anchored?

 

What do they do?

Great Tensile Strength: Enable cells to withstand mechanical stress

Where are they found?

1. Cytoplasm of most cells

2. Nuclear lamina (nuclear envelope)

Where are they anchored?

Anchored to the plasma membrane at cell-cell junctions

 

5

What is the configuration of proteins in intermediate filaments?

-8 staggered tetrameres form a region

-Will stagger to another 8 staggered tetrameric region in the growing strand

-Stabilized by acessory proteins 

6

What causes progeria?

Mutations in nuclear lamina that causes cellular aging 

7

In what three forms are cytoplasmic intermediate filaments found in cellss?

Epithelium: Keratin filaments

CT/Muscle/Glial Cells: Vimentin filaments

Nerve Cells: Neurofilaments

8

What role do intermediate filaments play in the nucleus?

They form the nuclear lamina

9

What is the role of microtubules in the cell?

-Vital to organization

-Form the mitotic spindle for chromosome segregation

-Part of cilia and flagella

10

On what end of a microtubule do you find gamma-tubulin?

The minus end (serves as an anchoring point)

11

Which end of a microtubule has faster growth?

Plus end

12

What configuration of protiens makes up a microtubule?

Rings of alpha and beta tubulin stacked on top of each other

13

What serves as the branching off point for microtubules at the centrosome?

Small rings of gamma-tubulin on the outside of the centrosome matrix

14

What stablizes microtubules at the distal end?

Microtubule capping protien

15

What does Taxol do?

Binds and stabilizes microtubules (prevents excess growth)

Microtubules are like taxis for dynein. Taxol keeps those taxis going.

16

What does Colchine and Vinblastine do?

Binds tubulin dimers and prevent their polymerization 

Tubulin would like to get a job as a microtubule, but it can't because of its CV

BLAST! CHRIST! I can't get a job!

17

Microfilaments:

1. What are they made of?

2. What can help them become stable?

3. What do they do?

1. What are they made of?

F-Actin is made of a twisted polymer of G-Actin (globular actin)

2. What can help them become stable?

They are often unstable unless associated with other protiens

3. What do they do?

Cell movements: locomotion, phagocytosis, cell division, contraction, etc

18

What end of a Microfilament sees more growth?

Plus end

19

What does Phalloidin do?

Where might it be found in nature?

What can it be used for?

What does Phalloidin do?

Binds and stabilizes microfilaments (actin)

Where might it be found in nature?

Deathcap Mushroom

What can it be used for?

Used in microscopy to stabilize actin for visualization

20

What does cytochalasin do?

What does latrunculin do?

What does cytochalasin do?

Prevents the plus end of an actin filament from polymerizing by capping the end

What does latrunculin do?

Prevents actin monomers from polymerizing by binding to them

 

21

What are the basal laminae of cells made of?

Collagen

(Collagen IV and Laminin, primarily)

 

22

How is collagen arranged?

Homotrimers or Heterotrimers that form collagenous Triple Helix

-organized as fibers, sheets, transmembrane structures

23

What triggers the self assembly of collagen?

Where is this collagen synthesized?

Where is it triggered to self assemble?

What triggers the self assembly of collagen?

Cleavage of procollagen's amino- and carboxy - terminal extentions

Where is this collagen synthesized?

In cell

Where is it triggered to self assemble?

In the extracellular space

Note: the triple helix forms in the rough ER, but forming into fibrils and fibers happens in the extracellular space.

24

What diseases are associated with collagen dysfunctions?

 

Scurvy and Ehlers-Danlos Syndrome

25

Adherens Junctions

1. What is the adhesion type?

2. What is the principal cell adhesion molecule (CAM) / adhesion receptor?

3. What is the cytoskeletal attachment?

4. What is the function?

1. What is the adhesion type?

Cell to cell

2. What is the principal cell adhesion molecule (CAM) / adhesion receptor?

Cadherines

3. What is the cytoskeletal attachment?

Actin filaments

4. What is the function?

Shape, tension, singnaling, shearing force resistance

26

Cadherins

1. What do they work together to form?

2. What two junctions do they make?

3. What do they interact with?

1. What do they work together to form?

Epithelial Sheets

2. What two junctions do they make?

Adhere junctions and desmosomes

3. What do they interact with?

Other cadherins (homophilic) and actin in the cytoskeleton

27

What cadherins are related in transitional bladder cancer?

What does this change correspond with?

A decrease in E-cadherin and an increase in N-Cadherin

-Corresponds with an increase in invasiveness

28

For Desmosomes

1. What is the adhesion type?

2. What is the principal cell adhesion molecule (CAM) / adhesion receptor?

3. What is the cytoskeletal attachment?

4. What is the function?

1. What is the adhesion type?

Cell to Cell

2. What is the principal cell adhesion molecule (CAM) / adhesion receptor?

Desmosome Cadherins

3. What is the cytoskeletal attachment?

Intermediate Filaments

4. What is the function?

Strength, durability, signaling

29

Hemidesmosomes

1. What is the adhesion type?

2. What is the principal cell adhesion molecule (CAM) / adhesion receptor?

3. What is the cytoskeletal attachment?

4. What is the function?

1. What is the adhesion type?

Cell to Matrix

2. What is the principal cell adhesion molecule (CAM) / adhesion receptor?

Integrin (alpha6beta4)

3. What is the cytoskeletal attachment?

Intermediate Filaments

4. What is the function?

Shape, rigidity, signaling

30

Tight Junctions

1. What is the adhesion type?

2. What is the principal cell adhesion molecule (CAM) / adhesion receptor?

3. What is the cytoskeletal attachment?

4. What is the function?

1. What is the adhesion type?

Cell to Cell

2. What is the principal cell adhesion molecule (CAM) / adhesion receptor?

Occludin and Claudin

3. What is the cytoskeletal attachment?

Actin Filaments

4. What is the function?

Controlling solute flow, signalling