8. Tissue Architecture Flashcards

1
Q

Why might intermediate cytoskeletal filaments be resistant to stretching forces?

A

Because lateral contacts dominate in the organization of fibers, preventing stretching.

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2
Q

For intermediate filaments:

What do they do?

Where are they found?

Where are they anchored?

A

Enable cells to withstand mechanical stress (Great tensile strength)

Cytoplasm of most cells

Anchored to the plasma membrane at cell - cell junctions.

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3
Q

What configuration of protiens do you find in an intermediate filament?

A

8 staggered tetrameres form a region, which staggers to another 8 staggered tetrameric region in the growing strand.

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4
Q

In what disease might you find mutations affecting the basal lamina?

A

Progeria

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5
Q

What three structures do intermediate filaments make up in the cytoplasm of cells?

A

Keratin filaments

Vimentin (and vimentin-related) filaments

Neurofilaments

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6
Q

What role do intermediate filaments play in the nucleus?

A

They form the nuclear lamina

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7
Q

What roles to microtubules play in the cell?

A

They are vital to organization.

They form the mitotic spindle for chromosome segregation

They are part of cilia and flagella

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8
Q

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

A

The minus end

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9
Q

On which end of a microtubule might you see faster growth?

A

The plus end

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10
Q

What configuration of protiens makes up a microtubule?

A

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

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11
Q

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

A

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

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12
Q

What stablizes microtubules at the distal end?

A

Microtubule capping protien

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13
Q

What does Taxol do?

A

Binds and stabilizes microtubules

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

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14
Q

What four drugs mentioned in the slides bind tubulin dimers and prevent their polymerization?

A

Colchicine / Colcemid

Vinblastine / Vincristine

  • 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!*
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15
Q

For Microfilaments:

What are they made of?

What can help them become stable?

What do they do?

A

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

They are often unstable unless associated with other protiens

They are associated with cell movements (locomotion, phagocytosis, cell division, contraction, etc)

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16
Q

What end of a Microfilament sees more growth?

A

The plus end.

17
Q

What does Phalloidin do?

Where might it be found in nature?

What can it be used for?

A

Binds and stabilizes microfilaments (actin)

Deathcap Mushroom

Used in microscopy to stabilize actin for visualization

18
Q

What does cytochalasin do?

What does latrunculin do?

A

Prevents the plus end of an actin filament from polymerizing.

Actin in the cell (cyto) gets heated (-chal) because it didn’t get the A+ (plus end)

Prevents actin monomers from polymerizing.

Keeps the lats from attaching to the trunk.

19
Q

What are the basal laminae of cells made of?

A

Collagen

(Collagen IV and Laminin, primarily)

Note: In tutoring, we were expected to know what specific collagens did what. Creamer did not highlight that, or even present that, in his lectures.

20
Q

What arrangement does collagen take?

A

Homo OR Hetero - dimer

Triple Helix

21
Q

What triggers the self assembly of collagen?

Where is this collagen synthesized?

Where is it triggered to self assemble?

A

Cleavage of procollagen’s amino- and carboxy - terminal extentions.

In the cell

In the extracellular space

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

22
Q

What disease is associated with a failure to hydroxylate collagen?

What causes this failure?

What are the main symptoms?

A

Scurvy

Lack of cofactor (vitamin C)

  • Bleeding / opening of wounds
  • Teeth falling out
23
Q

For Ehlers-Danlos Syndrome

What is defective?

What happens as a result?

A

Collagen or collagen synthesis genes.

Skin is very stretchy, joints are hypermobile, bones, blood vessels, and organs can all be weaker.

24
Q

For Adherens Junctions

What is the adhesion type?

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

What is the cytoskeletal attachment?

What is the function?

A

Cell to Cell

Cadherins

Actin filaments

Shape, tension, singnaling, shearing force resistance

25
For **Desmosomes** What is the adhesion type? What is the principal cell adhesion molecule (CAM) / adhesion receptor? What is the cytoskeletal attachment? What is the function?
Cell - Cell Desmosome Cadherens Intermediate filaments Strength, durability, signaling
26
For **Hemidesmosomes** What is the adhesion type? What is the principal cell adhesion molecule (CAM) / adhesion receptor? What is the cytoskeletal attachment? What is the function?
Cell - Matrix Integrin (**alpha**6**beta**4) Intermediate filaments Shape, rigidity, signaling
27
For **Tight Junctions** What is the adhesion type? What is the principal cell adhesion molecule (CAM) / adhesion receptor? What is the cytoskeletal attachment? What is the function?
Cell to Cell Occludin, claudin Actin filaments Controlling solute flow, signalling
28
For **Gap Junctions** What is the adhesion type? What is the principal cell adhesion molecule (CAM) / adhesion receptor? What is the cytoskeletal attachment? What is the function?
Cell to Cell Connexins, innexins, pannexins Attach via adapters to other junctions Communication, small molecule transfer between cells
29
What is E Cadherin? What is N Cadherin? What is VE Cadherin? What is LI Cadherin? Which ones are typical vs atypical?
Epithelial cadherin Neuronal cadherin Vascular Endothelial cadherin Liver-Intestine cadherin All of these are typical except for liver-intestine, which is atypical
30
For all **Cadherins** What do they work together to form? What two junctions do they make? What do they interact with?
Epithelial sheets Adherens junctions and desmosomes Other cadherins (homophilic) and actin in the cytoskeleton
31
What cadheren related phenominon do we see in transitional bladder cancer? What does this change correspond with?
A decrease in E-cadherin and an increase in N-Cadherin This change corresponds with an increase in invasiveness.
32
What is Epithelia to Mysenchymal Transition?
Change of cell shape from epithelial shape to a more mesenchymal shape in invasive cancer.
33
What is the special job of the Ig superfamily of CAMs? What kind of binding are they capable of?
Interaction with immune cells Both heterophilic and homophilic binding
34
What two main roles do **selectins** perform in immune response? What are selectins dependent upon? What increases presentation of selectins?
Assisting in **rolling adhesion** (low affinity slowing of leukocytes) and binding of **extracellular carbohydrates** **Calcium** (they are calcium dependent glycoprotiens) Local **inflammation**
35
What role do Integrins play in rolling adhesion?
They are the high affinity stops after selectins slow the leukocyte down. They use the **beta2** family of integrins.
36
Other than rolling adhesion, what two other functions can Integrins perform?
They **couple the extracellular matrix to the cytoskeleton** using fibronectin, collagen, laminin, and vitronectin. (Aids in enduring pulling forces) They can **activate signalling pathways** through interactions with receptor tyrosine kinase, which allows them to regulate growth, division, survival, differentiation, and apoptosis. *(Everything we talked about last week)*