Tissue Architechture Flashcards
What are the four main functions of the cytoskeleton?
They are:
- Dynamic
- Adaptable
- Stable
- Strong
What are the three types of cytoskeletal filaments?
- intermediate filaments
- microtubules
- microfilaments
What do intermediate filaments do and what is an example?
They have great tensile strength (rope like), bear mechanical stress, cell to cell communication, form nuclear lamina
What are examples of different types of intermediate filaments?
keratin in epithelial
vimentin in connective tissues
neurofilaments in nerve cells
nuclear lamins
What happens if someone has a mutation in their nuclear lamina?
Leads to progeria = accelerated aging
What are the key roles of microtubules?
used in mitotic spindle
cilia/flagella movement
organization*
How are microtubules made?
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
What does the microtubule specific durg Taxol do?
binds and stabilizes microtubules, preventing growth of cell so cells dont divide
What are the key roles of microfilaments?
make actin filaments (F-actin, polymer of Gactin), important for polarity and movement
What does the actin specific drug Phalloidin do?
binds and stabilizes filaments whic makes the visualization of actin cytoskeleton easy
What are the results of the different types of proteins that bind to and modify actin properties?
Stabilization
Strengthen
Cross-linking
Oragnization
What do proteoglycans do?
part of the extracellular matrix, allows cell to cell interactions
What are the types of collagen?
sheet forming (type IV) Fibrillar collagens (types 1,2,3,5) forms triple helix, located at the basement membrane
What do laminin and fibronectin do?
multi-adhesive matrix proteins : they are found at the basement membrane with collagen
What are the ECM functions (6)?
- Anchoring
- Biomechanical
- Polarity
- Migration
- Growth Factors
- Proteolytic Clevage
Why is collagen important to the ECM?
Main structual protein in ECM/connective tissue and basal laminae
When collagen is produced, is it active? When does it become active?
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)
What is need so scurvy does not occur?
Prolyl hydroxylase or lysl hydroxylase (wont form collagen correctly) which requires Fe and ascorbate as co factors
What causes Ehlers-Danlos?
A mutation in collagen’s fibrous protein or enzymes that results in extremely stechy skin :)
What do anchoring junctions do and what CAMs are anchoring?
Anchor cells to neighboring cells and membrane basement.
Cadherins, Desmosomal cadherins, integrins
What do occluding junctions do?
also known as tight junction, control solute flow (occludin claudin)
What do signal-relaying junctions do?
communicate by sending small molecules across (neuronal) (connexins)
What do channel forming junctions do?
create channel between cells
What are the three major domains of cell adhesion molecules (CAMs)?
Extracellular
Transmembrane
Cytoplasmic
What are characteristics of cadherins (adheren junctions)?
They are all Ca2+ dependent adhesion moledcules, important in forming junctions between cells. make homophilic interactions
What are the types of different cadherens?(4)
E-cadherin (epithelial)
N-cadherin (neural)
VE-cadherin (vascular-endothelial)
LI-cadherin (liver-intestine) (ATYPICAL)
What does EMT stand for and what cadherins will tell you how invasive a cancer is?
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
What is the role of Ig superfamily CAMs?
they interact with immune cells (Ca independent)
Waht kind of binding are Ig CAMs capable of ?
Heterophilic and homophilic binding
What two roles do selectins perform in immune repsonse?
Assist in rolling adhesion (low affinity slowing of leukocytes (WBC)) and binding of extracellular carbohydrates
What are selectins dependent on?
Calcium dependent (glycoproteins!)
What increases the presence of selectins?
infalmmation
What role do integrins play in rolling adehsion?
They are the high affinity stops after selectins slow the leukocyte down. Using beta2 family of integrins
What other two functions do integrins perform?
they couple extracellular matrix to the cytoskeleton using fibronectin, collagen, and laminin.
They activate signaling pathways through RTK
What proteins are needed for cell-matrix ?
Integrins
What proteins are needed for cell-cell junctions?
Cadherins/desmosomal cadherins, occludins, connexins
