Tissue Architecture Flashcards
What is more stable - a single protofilament or multiple protofilaments?
Multiple Protofilaments
-single ones are thermally unstable
Why might intermediate cytoskeletal filaments be resistant to stretching forces?
Lateral contacts dominate in the organization of fibers, preventing stretching
-Rope like properties
What are the three types of Cytoskeletal Filaments?
- Intermediate Filaments
- Microtubules
- Microfilaments
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
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
What causes progeria?
Mutations in nuclear lamina that causes cellular aging
In what three forms are cytoplasmic intermediate filaments found in cellss?
Epithelium: Keratin filaments
CT/Muscle/Glial Cells: Vimentin filaments
Nerve Cells: Neurofilaments
What role do intermediate filaments play in the nucleus?
They form the nuclear lamina
What is the role of microtubules in the cell?
- Vital to organization
- Form the mitotic spindle for chromosome segregation
- Part of cilia and flagella
On what end of a microtubule do you find gamma-tubulin?
The minus end (serves as an anchoring point)
Which end of a microtubule has faster growth?
Plus end
What configuration of protiens makes up a microtubule?
Rings of alpha and beta tubulin stacked on top of each other
What serves as the branching off point for microtubules at the centrosome?
Small rings of gamma-tubulin on the outside of the centrosome matrix
What stablizes microtubules at the distal end?
Microtubule capping protien
What does Taxol do?
Binds and stabilizes microtubules (prevents excess growth)
Microtubules are like taxis for dynein. Taxol keeps those taxis going.
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!*
Microfilaments:
- What are they made of?
- What can help them become stable?
- 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
What end of a Microfilament sees more growth?
Plus end
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
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
What are the basal laminae of cells made of?
Collagen
(Collagen IV and Laminin, primarily)
How is collagen arranged?
Homotrimers or Heterotrimers that form collagenous Triple Helix
-organized as fibers, sheets, transmembrane structures
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.
What diseases are associated with collagen dysfunctions?
Scurvy and Ehlers-Danlos Syndrome
